code: public BaasDocument merge(JsonObject other) {
          JsonObject o = checkObject(other);
          data.merge(o);
          return this;
      }
docs: Merges the content of <code>other</code> into this
  document overwriting any mapping for wich other contains a key.
  Note that other is copied before merging.
  
  @param other {@link com.baasbox.android.json.JsonObject}
  @return this document with <code>other</code> mappings merged in