java GSON未为无效输入引发错误

Question

我有以下代码行：

    private final Type type = new TypeToken<List<MyBody>>() {}.getType();
    private final Gson gson;

MyBody:

package org.apache.flume.util;

import java.io.Serializable;
import java.util.Date;
import java.util.Map;

public class PEGBody implements Serializable {
  public Body(String event_id, String metricName, float value, Map<String, String> dimensions,
                 long timestamp_ms) {
    this.event_id = event_id;
    this.metric_name = metricName;
    this.value = value;
    this.dimensions = dimensions;
    this.timestamp_ms = timestamp_ms;
  }

  private final String event_id;
  private final String metric_name;
  private final float value;
  private final Map<String, String> dimensions;
  private final long timestamp_ms;

 // getters and setters

}

最后，我在阅读请求：

 try {
      data = gson.fromJson(reader, type);
    }
    catch (JsonSyntaxException ex) {
      throw new HTTPBadRequestException("Request has invalid JSON Syntax.", ex);
    }

当我们在请求中缺少任何对象时，它不会抛出错误，比如说我没有 metric_name在请求中，它没有抛出无效的请求错误。关于这个问题有什么帮助吗