OPENJPA-2862 select SUM return types fixed

As per spec section 4.8.5 Aggregate Functions in the SELECT
clause we need to handle a few types in a special way

openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/exps/Sum.java

@@ -35,13 +35,26 @@ class Sum extends NullableAggregateUnaryOp { // OPENJPA-1794
         super(val);
     }
 
+    /**
+     * As per spec section 4.8.5 Aggregate Functions in the SELECT Clause we
+     * need to handle a few types in a special way.
+     */
     @Override
     protected Class getType(Class c) {
-        Class wrap = Filters.wrap(c);
-        if (wrap == Integer.class
-            || wrap == Short.class
-            || wrap == Byte.class)
-            return long.class;
+        if (c == Integer.class ||
+            c == int.class ||
+            c == Short.class ||
+            c == short.class ||
+            c == Byte.class ||
+            c == byte.class) {
+            return Long.class;
+        }
+        if (c == Float.class ||
+            c == float.class ||
+            c == Double.class ||
+            c == double.class ) {
+            return Double.class;
+        }
         return c;
     }