Merge branch 'master' into 3.0.0

# Conflicts:
#	redisson/src/main/java/org/redisson/api/RLexSortedSetReactive.java

redisson/src/main/java/org/redisson/api/RLexSortedSet.java

@@ -25,8 +25,19 @@ import java.util.Collection;
  */
 public interface RLexSortedSet extends RLexSortedSetAsync, RSortedSet<String>, RExpirable {
     
+    /**
+     * Removes and returns the head element or {@code null} if this sorted set is empty.
+     *
+     * @return the head element, 
+     *         or {@code null} if this sorted set is empty
+     */
     String pollFirst();
 
+    /**
+     * Removes and returns the tail element or {@code null} if this sorted set is empty.
+     *
+     * @return the tail element or {@code null} if this sorted set is empty
+     */
     String pollLast();
 
     /**
@@ -37,44 +48,210 @@ public interface RLexSortedSet extends RLexSortedSetAsync, RSortedSet<String>, R
      */
     Integer revRank(String o);
     
+    /**
+     * Removes tail values range starting with <code>fromElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @return number of elements removed
+     */
     int removeRangeTail(String fromElement, boolean fromInclusive);
 
+    /**
+     * Removes head values range ending with <code>toElement</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return number of elements removed
+     */
     int removeRangeHead(String toElement, boolean toInclusive);
 
+    /**
+     * Removes values range starting with <code>fromElement</code> and ending with <code>toElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return number of elements removed
+     */
     int removeRange(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive);
 
+    /**
+     * Returns the number of tail values starting with <code>fromElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @return number of elements
+     */
     int countTail(String fromElement, boolean fromInclusive);
 
+    /**
+     * Returns the number of head values ending with <code>toElement</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return number of elements
+     */
     int countHead(String toElement, boolean toInclusive);
 
+    /**
+     * Returns tail values range starting with <code>fromElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @return collection of elements
+     */
     Collection<String> rangeTail(String fromElement, boolean fromInclusive);
 
+    /**
+     * Returns head values range ending with <code>toElement</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     Collection<String> rangeHead(String toElement, boolean toInclusive);
 
+    /**
+     * Returns values range starting with <code>fromElement</code> and ending with <code>toElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     Collection<String> range(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive);
 
+    /**
+     * Returns tail values range starting with <code>fromElement</code>. 
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param offset - offset of result collection
+     * @param count - amount of result collection
+     * @return collection of elements
+     */
     Collection<String> rangeTail(String fromElement, boolean fromInclusive, int offset, int count);
 
+    /**
+     * Returns head values range ending with <code>toElement</code>.
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @param offset - offset of result collection
+     * @param count - amount of result collection
+     * @return collection of elements
+     */
     Collection<String> rangeHead(String toElement, boolean toInclusive, int offset, int count);
 
+    /**
+     * Returns values range starting with <code>fromElement</code> and ending with <code>toElement</code>.
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     Collection<String> range(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive, int offset, int count);
 
+    /**
+     * Returns tail values range in reverse order starting with <code>fromElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @return collection of elements
+     */
     Collection<String> rangeTailReversed(String fromElement, boolean fromInclusive);
 
+    /**
+     * Returns head values range in reverse order ending with <code>toElement</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     Collection<String> rangeHeadReversed(String toElement, boolean toInclusive);
 
+    /**
+     * Returns values range in reverse order starting with <code>fromElement</code> and ending with <code>toElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     Collection<String> rangeReversed(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive);
 
+    /**
+     * Returns tail values range in reverse order starting with <code>fromElement</code>. 
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param offset - offset of result collection
+     * @param count - amount of result collection
+     * @return collection of elements
+     */
     Collection<String> rangeTailReversed(String fromElement, boolean fromInclusive, int offset, int count);
 
+    /**
+     * Returns head values range in reverse order ending with <code>toElement</code>.
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @param offset - offset of result collection
+     * @param count - amount of result collection
+     * @return collection of elements
+     */
     Collection<String> rangeHeadReversed(String toElement, boolean toInclusive, int offset, int count);
 
+    /**
+     * Returns values range in reverse order starting with <code>fromElement</code> and ending with <code>toElement</code>.
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     Collection<String> rangeReversed(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive, int offset, int count);
     
+    /**
+     * Returns the number of elements between <code>fromElement</code> and <code>toElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return number of elements
+     */
     int count(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive);
 
+    /**
+     * Returns rank of the element
+     * 
+     * @param o - element to rank
+     * @return rank or <code>null</code> if element does not exist
+     */
     Integer rank(String o);
 
+    /**
+     * Returns values by rank range. Indexes are zero based. 
+     * <code>-1</code> means the highest score, <code>-2</code> means the second highest score.
+     * 
+     * @param startIndex - start index 
+     * @param endIndex - end index
+     * @return collection of elements
+     */
     Collection<String> range(int startIndex, int endIndex);
 
 }

redisson/src/main/java/org/redisson/api/RLexSortedSetAsync.java

@@ -18,19 +18,40 @@ package org.redisson.api;
 import java.util.Collection;
 
 /**
- * Sorted set contained values of String type
+ * Async interface for sorted set contained values of String type.
  * 
  * @author Nikita Koksharov
  *
  */
 public interface RLexSortedSetAsync extends RCollectionAsync<String> {
 
+    /**
+     * Removes and returns the tail element or {@code null} if this sorted set is empty.
+     *
+     * @return the tail element or {@code null} if this sorted set is empty
+     */
     RFuture<String> pollLastAsync();
 
+    /**
+     * Removes and returns the head element or {@code null} if this sorted set is empty.
+     *
+     * @return the head element, 
+     *         or {@code null} if this sorted set is empty
+     */
     RFuture<String> pollFirstAsync();
 
+    /**
+     * Returns the first element.
+     *
+     * @return element
+     */
     RFuture<String> firstAsync();
 
+    /**
+     * Returns the last element.
+     *
+     * @return element
+     */
     RFuture<String> lastAsync();
     
     /**
@@ -40,44 +61,210 @@ public interface RLexSortedSetAsync extends RCollectionAsync<String> {
      */
     RFuture<Collection<String>> readAllAsync();
     
+    /**
+     * Removes values range starting with <code>fromElement</code> and ending with <code>toElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return number of elements removed
+     */
     RFuture<Integer> removeRangeAsync(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive);
 
+    /**
+     * Removes tail values range starting with <code>fromElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @return number of elements removed
+     */
     RFuture<Integer> removeRangeTailAsync(String fromElement, boolean fromInclusive);
 
+    /**
+     * Removes head values range ending with <code>toElement</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return number of elements removed
+     */
     RFuture<Integer> removeRangeHeadAsync(String toElement, boolean toInclusive);
 
+    /**
+     * Returns the number of tail values starting with <code>fromElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @return number of elements
+     */
     RFuture<Integer> countTailAsync(String fromElement, boolean fromInclusive);
 
+    /**
+     * Returns the number of head values ending with <code>toElement</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return number of elements
+     */
     RFuture<Integer> countHeadAsync(String toElement, boolean toInclusive);
 
+    /**
+     * Returns tail values range starting with <code>fromElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @return collection of elements
+     */
     RFuture<Collection<String>> rangeTailAsync(String fromElement, boolean fromInclusive);
 
+    /**
+     * Returns head values range ending with <code>toElement</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     RFuture<Collection<String>> rangeHeadAsync(String toElement, boolean toInclusive);
 
+    /**
+     * Returns values range starting with <code>fromElement</code> and ending with <code>toElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     RFuture<Collection<String>> rangeAsync(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive);
 
+    /**
+     * Returns tail values range starting with <code>fromElement</code>. 
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param offset - offset of result collection
+     * @param count - amount of result collection
+     * @return collection of elements
+     */
     RFuture<Collection<String>> rangeTailAsync(String fromElement, boolean fromInclusive, int offset, int count);
     
+    /**
+     * Returns head values range ending with <code>toElement</code>.
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @param offset - offset of result collection
+     * @param count - amount of result collection
+     * @return collection of elements
+     */
     RFuture<Collection<String>> rangeHeadAsync(String toElement, boolean toInclusive, int offset, int count);
 
+    /**
+     * Returns values range starting with <code>fromElement</code> and ending with <code>toElement</code>.
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     RFuture<Collection<String>> rangeAsync(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive, int offset, int count);
     
+    /**
+     * Returns tail values range in reverse order starting with <code>fromElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @return collection of elements
+     */
     RFuture<Collection<String>> rangeTailReversedAsync(String fromElement, boolean fromInclusive);
 
+    /**
+     * Returns head values range in reverse order ending with <code>toElement</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     RFuture<Collection<String>> rangeHeadReversedAsync(String toElement, boolean toInclusive);
 
+    /**
+     * Returns values range in reverse order starting with <code>fromElement</code> and ending with <code>toElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     RFuture<Collection<String>> rangeReversedAsync(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive);
 
+    /**
+     * Returns tail values range in reverse order starting with <code>fromElement</code>. 
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param offset - offset of result collection
+     * @param count - amount of result collection
+     * @return collection of elements
+     */
     RFuture<Collection<String>> rangeTailReversedAsync(String fromElement, boolean fromInclusive, int offset, int count);
     
+    /**
+     * Returns head values range in reverse order ending with <code>toElement</code>.
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @param offset - offset of result collection
+     * @param count - amount of result collection
+     * @return collection of elements
+     */
     RFuture<Collection<String>> rangeHeadReversedAsync(String toElement, boolean toInclusive, int offset, int count);
 
+    /**
+     * Returns values range in reverse order starting with <code>fromElement</code> and ending with <code>toElement</code>.
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     RFuture<Collection<String>> rangeReversedAsync(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive, int offset, int count);
 
+    /**
+     * Returns the number of elements between <code>fromElement</code> and <code>toElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return number of elements
+     */
     RFuture<Integer> countAsync(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive);
 
+    /**
+     * Returns rank of the element
+     * 
+     * @param o - element to rank
+     * @return rank or <code>null</code> if element does not exist
+     */
     RFuture<Integer> rankAsync(String o);
 
+    /**
+     * Returns values by rank range. Indexes are zero based. 
+     * <code>-1</code> means the highest score, <code>-2</code> means the second highest score.
+     * 
+     * @param startIndex - start index 
+     * @param endIndex - end index
+     * @return collection of elements
+     */
     RFuture<Collection<String>> rangeAsync(int startIndex, int endIndex);
     
     /**

redisson/src/main/java/org/redisson/api/RLexSortedSetReactive.java

@@ -20,35 +20,134 @@ import java.util.Collection;
 import reactor.core.publisher.Mono;
 
 /**
- * Reactive interface for LexSortedSet object
+ * Reactive interface for sorted set contained values of String type.
  * 
  * @author Nikita Koksharov
  *
  */
 public interface RLexSortedSetReactive extends RScoredSortedSetReactive<String>, RCollectionReactive<String> {
 
+    /**
+     * Removes values range starting with <code>fromElement</code> and ending with <code>toElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return number of elements removed
+     */
     Mono<Integer> removeRange(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive);
 
+    /**
+     * Removes tail values range starting with <code>fromElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @return number of elements removed
+     */
     Mono<Integer> removeRangeTail(String fromElement, boolean fromInclusive);
 
+    /**
+     * Removes head values range ending with <code>toElement</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return number of elements removed
+     */
     Mono<Integer> removeRangeHead(String toElement, boolean toInclusive);
 
+    /**
+     * Returns the number of tail values starting with <code>fromElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @return number of elements
+     */
     Mono<Integer> countTail(String fromElement, boolean fromInclusive);
 
+    /**
+     * Returns the number of head values ending with <code>toElement</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return number of elements
+     */
     Mono<Integer> countHead(String toElement, boolean toInclusive);
 
+    /**
+     * Returns tail values range starting with <code>fromElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @return collection of elements
+     */
     Mono<Collection<String>> rangeTail(String fromElement, boolean fromInclusive);
 
+    /**
+     * Returns head values range ending with <code>toElement</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     Mono<Collection<String>> rangeHead(String toElement, boolean toInclusive);
 
+    /**
+     * Returns values range starting with <code>fromElement</code> and ending with <code>toElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     Mono<Collection<String>> range(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive);
 
+    /**
+     * Returns tail values range starting with <code>fromElement</code>. 
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param offset - offset of result collection
+     * @param count - amount of result collection
+     * @return collection of elements
+     */
     Mono<Collection<String>> rangeTail(String fromElement, boolean fromInclusive, int offset, int count);
 
+    /**
+     * Returns head values range ending with <code>toElement</code>.
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @param offset - offset of result collection
+     * @param count - amount of result collection
+     * @return collection of elements
+     */
     Mono<Collection<String>> rangeHead(String toElement, boolean toInclusive, int offset, int count);
 
+    /**
+     * Returns values range starting with <code>fromElement</code> and ending with <code>toElement</code>.
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     Mono<Collection<String>> range(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive, int offset, int count);
 
+    /**
+     * Returns the number of elements between <code>fromElement</code> and <code>toElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return number of elements
+     */
     Mono<Integer> count(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive);
 
 }

redisson/src/main/java/org/redisson/api/RLexSortedSetRx.java

@@ -20,35 +20,134 @@ import java.util.Collection;
 import io.reactivex.Flowable;
 
 /**
- * RxJava2 interface for LexSortedSet object
+ * RxJava2 interface for sorted set contained values of String type.
  * 
  * @author Nikita Koksharov
  *
  */
 public interface RLexSortedSetRx extends RScoredSortedSetRx<String>, RCollectionRx<String> {
 
+    /**
+     * Removes values range starting with <code>fromElement</code> and ending with <code>toElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return number of elements removed
+     */
     Flowable<Integer> removeRange(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive);
 
+    /**
+     * Removes tail values range starting with <code>fromElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @return number of elements removed
+     */
     Flowable<Integer> removeRangeTail(String fromElement, boolean fromInclusive);
 
+    /**
+     * Removes head values range ending with <code>toElement</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return number of elements removed
+     */
     Flowable<Integer> removeRangeHead(String toElement, boolean toInclusive);
 
+    /**
+     * Returns the number of tail values starting with <code>fromElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @return number of elements
+     */
     Flowable<Integer> countTail(String fromElement, boolean fromInclusive);
 
+    /**
+     * Returns the number of head values ending with <code>toElement</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return number of elements
+     */
     Flowable<Integer> countHead(String toElement, boolean toInclusive);
 
+    /**
+     * Returns tail values range starting with <code>fromElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @return collection of elements
+     */
     Flowable<Collection<String>> rangeTail(String fromElement, boolean fromInclusive);
 
+    /**
+     * Returns head values range ending with <code>toElement</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     Flowable<Collection<String>> rangeHead(String toElement, boolean toInclusive);
 
+    /**
+     * Returns values range starting with <code>fromElement</code> and ending with <code>toElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     Flowable<Collection<String>> range(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive);
 
+    /**
+     * Returns tail values range starting with <code>fromElement</code>. 
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param offset - offset of result collection
+     * @param count - amount of result collection
+     * @return collection of elements
+     */
     Flowable<Collection<String>> rangeTail(String fromElement, boolean fromInclusive, int offset, int count);
 
+    /**
+     * Returns head values range ending with <code>toElement</code>.
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @param offset - offset of result collection
+     * @param count - amount of result collection
+     * @return collection of elements
+     */
     Flowable<Collection<String>> rangeHead(String toElement, boolean toInclusive, int offset, int count);
 
+    /**
+     * Returns values range starting with <code>fromElement</code> and ending with <code>toElement</code>.
+     * Returned collection limited by <code>count</code> and starts with <code>offset</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return collection of elements
+     */
     Flowable<Collection<String>> range(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive, int offset, int count);
 
+    /**
+     * Returns the number of elements between <code>fromElement</code> and <code>toElement</code>.
+     * 
+     * @param fromElement - start element
+     * @param fromInclusive - start element inclusive
+     * @param toElement - end element
+     * @param toInclusive - end element inclusive
+     * @return number of elements
+     */
     Flowable<Integer> count(String fromElement, boolean fromInclusive, String toElement, boolean toInclusive);
 
 }