Fixed issue with proxy generation

CHANGES

@@ -1,5 +1,11 @@
 HikariCP Changes
 
+Changes in 2.4.2
+
+ * Fixed issue with proxy generation whereby the generated classes contain the
+   major version number for Java 8, which makes them incompatible with the Java 7
+   runtime.
+
 Changes in 2.4.1
 
  * issue 380: housekeeper was not being scheduled in the case of a user specified

src/main/java/com/zaxxer/hikari/util/JavassistProxyFactory.java

@@ -42,6 +42,7 @@ import javassist.CtNewMethod;
 import javassist.LoaderClassPath;
 import javassist.Modifier;
 import javassist.NotFoundException;
+import javassist.bytecode.ClassFile;
 
 /**
  * This class generates the proxy objects for {@link Connection}, {@link Statement},
@@ -190,6 +191,7 @@ public final class JavassistProxyFactory
          }
       }
 
+      targetCt.getClassFile().setMajorVersion(ClassFile.JAVA_7);
       targetCt.writeFile("target/classes");
    }