Merge pull request #44 from arturobernalg/feature/final_var

Make final var.
diff --git a/src/main/java/org/apache/commons/ognl/OgnlRuntime.java b/src/main/java/org/apache/commons/ognl/OgnlRuntime.java
index 54a7a5f..cb65f5e 100644
--- a/src/main/java/org/apache/commons/ognl/OgnlRuntime.java
+++ b/src/main/java/org/apache/commons/ognl/OgnlRuntime.java
@@ -122,7 +122,7 @@
      */
     private static final String NULL_OBJECT_STRING = "<null>";
 
-    static OgnlCache cache = new OgnlCache();
+    static final OgnlCache cache = new OgnlCache();
 
     private static final PrimitiveTypes primitiveTypes = new PrimitiveTypes();
 
diff --git a/src/main/java/org/apache/commons/ognl/internal/entry/GenericMethodParameterTypeCacheEntry.java b/src/main/java/org/apache/commons/ognl/internal/entry/GenericMethodParameterTypeCacheEntry.java
index b3c4ca7..7e7d424 100644
--- a/src/main/java/org/apache/commons/ognl/internal/entry/GenericMethodParameterTypeCacheEntry.java
+++ b/src/main/java/org/apache/commons/ognl/internal/entry/GenericMethodParameterTypeCacheEntry.java
@@ -28,9 +28,9 @@
 public class GenericMethodParameterTypeCacheEntry
     implements CacheEntry
 {
-    Method method;
+    final Method method;
 
-    Class<?> type;
+    final Class<?> type;
 
     public GenericMethodParameterTypeCacheEntry( Method method, Class<?> type )
     {
diff --git a/src/main/java/org/apache/commons/ognl/internal/entry/MethodCacheEntry.java b/src/main/java/org/apache/commons/ognl/internal/entry/MethodCacheEntry.java
index cfb126a..cccaf78 100644
--- a/src/main/java/org/apache/commons/ognl/internal/entry/MethodCacheEntry.java
+++ b/src/main/java/org/apache/commons/ognl/internal/entry/MethodCacheEntry.java
@@ -26,7 +26,7 @@
 public class MethodCacheEntry
     implements CacheEntry
 {
-    public Class<?> targetClass;
+    public final Class<?> targetClass;
 
     public MethodCacheEntry( Class<?> targetClass )
     {
diff --git a/src/main/java/org/apache/commons/ognl/internal/entry/PermissionCacheEntry.java b/src/main/java/org/apache/commons/ognl/internal/entry/PermissionCacheEntry.java
index 52405dd..68c0890 100644
--- a/src/main/java/org/apache/commons/ognl/internal/entry/PermissionCacheEntry.java
+++ b/src/main/java/org/apache/commons/ognl/internal/entry/PermissionCacheEntry.java
@@ -28,7 +28,7 @@
 public class PermissionCacheEntry
     implements CacheEntry
 {
-    public Method method;
+    public final Method method;
 
     public PermissionCacheEntry( Method method )
     {