Remove a redundant condition and an empty string

Remove "NULL.equals(object)" on line 2756 of JSONObject.java since line 2752 has already tested it.
Remove the empty string on line 249 of JSONPointer.java.

Author: AlexCai2019

src/main/java/org/json/JSONObject.java

@@ -2752,8 +2752,7 @@ private static Object wrap(Object object, Set<Object> objectsRecord, int recursi
             if (NULL.equals(object)) {
                 return NULL;
             }
-            if (object instanceof JSONObject || object instanceof JSONArray
-                    || NULL.equals(object) || object instanceof JSONString
+            if (object instanceof JSONObject || object instanceof JSONArray || object instanceof JSONString
                     || object instanceof Byte || object instanceof Character
                     || object instanceof Short || object instanceof Integer
                     || object instanceof Long || object instanceof Boolean

src/main/java/org/json/JSONPointer.java

@@ -246,7 +246,7 @@ private static Object readByIndexToken(Object current, String indexToken) throws
      */
     @Override
     public String toString() {
-        StringBuilder rval = new StringBuilder("");
+        StringBuilder rval = new StringBuilder();
         for (String token: this.refTokens) {
             rval.append('/').append(escape(token));
         }