public Builder clearUpdateTime() {
      bitField0_ = (bitField0_ & ~0x00000004);
      updateTime_ = null;
      if (updateTimeBuilder_ != null) {
        updateTimeBuilder_.dispose();
        updateTimeBuilder_ = null;
      }
      onChanged();
      return this;
    }
<pre>
The time when the operation result was last updated.
</pre>

<code>.google.protobuf.Timestamp update_time = 6;</code>
java-vision/proto-google-cloud-vision-v1/src/main/java/com/google/cloud/vision/v1/OperationMetadata.java