sdk/src/com/socialize/google/gson/stream/JsonReader.java
public void nextNull() throws IOException {
    peek();
    if (token != JsonToken.NULL) {
      throw new IllegalStateException("Expected null but was " + token
          + " at line " + getLineNumber() + " column " + getColumnNumber());
    }

    advance();
  }
public void nextNull() throws IOException {
    peek();
    if (token != JsonToken.NULL) {
      throw new IllegalStateException("Expected null but was " + token
          + " at line " + getLineNumber() + " column " + getColumnNumber());
    }

    advance();
  }
Consumes the next token from the JSON stream and asserts that it is a
literal null.

@throws IllegalStateException if the next token is not null or if this
reader is closed.