openrtb-core/src/main/java/com/google/openrtb/json/OpenRtbJsonUtils.java
public static JsonToken peekStructStart(JsonParser par) throws IOException {
    JsonToken token = peekToken(par);
    if (token.isStructStart()) {
      return token;
    } else {
      throw new JsonParseException(par, "Expected start of array or object");
    }
  }
public static JsonToken peekStructStart(JsonParser par) throws IOException {
    JsonToken token = peekToken(par);
    if (token.isStructStart()) {
      return token;
    } else {
      throw new JsonParseException(par, "Expected start of array or object");
    }
  }
Skips a field name if necessary, returning the current token then, which must be
the start of an Array or Object: '{' or '['.