Document null writer contract for JSON encoding

Author: jmanico

core/src/main/java/org/owasp/encoder/Encode.java

@@ -1455,6 +1455,7 @@ public static String forJson(String input) {
      *
      * @param out where to write encoded output
      * @param input the input string to encode
+     * @throws NullPointerException if out is null
      * @throws IOException if thrown by writer
      * @since 1.5.0
      */