Mark fields final where appropriate

easy-rules-core/src/main/java/org/jeasy/rules/core/ActionMethodOrderBean.java

@@ -32,9 +32,9 @@ import java.lang.reflect.Method;
  */
 class ActionMethodOrderBean implements Comparable<ActionMethodOrderBean> {
 
-    private Method method;
+    private final Method method;
 
-    private int order;
+    private final int order;
 
     ActionMethodOrderBean(final Method method, final int order) {
         this.method = method;

easy-rules-core/src/main/java/org/jeasy/rules/core/DefaultRule.java

@@ -27,13 +27,12 @@ import org.jeasy.rules.api.Action;
 import org.jeasy.rules.api.Condition;
 import org.jeasy.rules.api.Facts;
 
-import java.util.ArrayList;
 import java.util.List;
 
 class DefaultRule extends BasicRule {
 
-    private Condition condition = Condition.FALSE;
-    private List<Action> actions = new ArrayList<>();
+    private final Condition condition;
+    private final List<Action> actions;
 
     DefaultRule(String name, String description, int priority, Condition condition, List<Action> actions) {
         super(name, description, priority);

easy-rules-core/src/main/java/org/jeasy/rules/core/InferenceRulesEngine.java

@@ -42,7 +42,7 @@ public final class InferenceRulesEngine extends AbstractRulesEngine {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(InferenceRulesEngine.class);
 
-    private DefaultRulesEngine delegate;
+    private final DefaultRulesEngine delegate;
 
     /**
      * Create a new inference rules engine with default parameters.

easy-rules-core/src/main/java/org/jeasy/rules/core/NoSuchFactException.java

@@ -25,7 +25,7 @@ package org.jeasy.rules.core;
 
 class NoSuchFactException extends RuntimeException {
 
-    private String missingFact;
+    private final String missingFact;
 
     public NoSuchFactException(String message, String missingFact) {
         super(message);

easy-rules-core/src/main/java/org/jeasy/rules/core/RuleBuilder.java

@@ -42,7 +42,7 @@ public class RuleBuilder {
     private int priority = Rule.DEFAULT_PRIORITY;
 
     private Condition condition = Condition.FALSE;
-    private List<Action> actions = new ArrayList<>();
+    private final List<Action> actions = new ArrayList<>();
 
     /**
      * Set rule name.

easy-rules-core/src/main/java/org/jeasy/rules/core/RuleProxy.java

@@ -48,7 +48,7 @@ import static java.lang.String.format;
  */
 public class RuleProxy implements InvocationHandler {
 
-    private Object target;
+    private final Object target;
     private String name;
     private String description;
     private Integer priority;
@@ -59,7 +59,7 @@ public class RuleProxy implements InvocationHandler {
     private Method toStringMethod;
     private org.jeasy.rules.annotation.Rule annotation;
 
-    private static RuleDefinitionValidator ruleDefinitionValidator = new RuleDefinitionValidator();
+    private static final RuleDefinitionValidator ruleDefinitionValidator = new RuleDefinitionValidator();
 
     private static final Logger LOGGER = LoggerFactory.getLogger(RuleProxy.class);
 

easy-rules-mvel/src/main/java/org/jeasy/rules/mvel/MVELAction.java

@@ -41,8 +41,8 @@ public class MVELAction implements Action {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(MVELAction.class);
 
-    private String expression;
-    private Serializable compiledExpression;
+    private final String expression;
+    private final Serializable compiledExpression;
 
     /**
      * Create a new {@link MVELAction}.

easy-rules-mvel/src/main/java/org/jeasy/rules/mvel/MVELCondition.java

@@ -37,7 +37,7 @@ import java.io.Serializable;
  */
 public class MVELCondition implements Condition {
 
-    private Serializable compiledExpression;
+    private final Serializable compiledExpression;
 
     /**
      * Create a new {@link MVELCondition}.

easy-rules-mvel/src/main/java/org/jeasy/rules/mvel/MVELRule.java

@@ -41,7 +41,7 @@ import java.util.List;
 public class MVELRule extends BasicRule {
 
     private Condition condition = Condition.FALSE;
-    private List<Action> actions = new ArrayList<>();
+    private final List<Action> actions = new ArrayList<>();
     private final ParserContext parserContext;
 
     /**

easy-rules-spel/src/main/java/org/jeasy/rules/spel/SpELRule.java

@@ -43,7 +43,7 @@ import java.util.List;
 public class SpELRule extends BasicRule {
 
     private Condition condition = Condition.FALSE;
-    private List<Action> actions = new ArrayList<>();
+    private final List<Action> actions = new ArrayList<>();
     private final ParserContext parserContext;
     private BeanResolver beanResolver;
 

easy-rules-support/src/main/java/org/jeasy/rules/support/composite/CompositeRule.java

@@ -45,7 +45,7 @@ public abstract class CompositeRule extends BasicRule {
      */
     protected Set<Rule> rules;
 
-    private Map<Object, Rule> proxyRules;
+    private final Map<Object, Rule> proxyRules;
 
     /**
      * Create a new {@link CompositeRule}.

easy-rules-support/src/main/java/org/jeasy/rules/support/reader/JsonRuleDefinitionReader.java

@@ -44,7 +44,7 @@ import java.util.Map;
 @SuppressWarnings("unchecked")
 public class JsonRuleDefinitionReader extends AbstractRuleDefinitionReader {
 
-    private ObjectMapper objectMapper;
+    private final ObjectMapper objectMapper;
 
     /**
      * Create a new {@link JsonRuleDefinitionReader}.

easy-rules-support/src/main/java/org/jeasy/rules/support/reader/YamlRuleDefinitionReader.java

@@ -46,7 +46,7 @@ import java.util.Map;
 @SuppressWarnings("unchecked")
 public class YamlRuleDefinitionReader extends AbstractRuleDefinitionReader {
 
-    private Yaml yaml;
+    private final Yaml yaml;
 
     /**
      * Create a new {@link YamlRuleDefinitionReader}.