public Builder mergeEndTime(com.google.protobuf.Duration value) {
      if (endTimeBuilder_ == null) {
        if (((bitField0_ & 0x00000002) != 0)
            && endTime_ != null
            && endTime_ != com.google.protobuf.Duration.getDefaultInstance()) {
          getEndTimeBuilder().mergeFrom(value);
        } else {
          endTime_ = value;
        }
      } else {
        endTimeBuilder_.mergeFrom(value);
      }
      if (endTime_ != null) {
        bitField0_ |= 0x00000002;
        onChanged();
      }
      return this;
    }
<pre>
Time offset relative to the beginning of the audio,
and corresponding to the end of the spoken word.
This field is only set if `enable_word_time_offsets=true` and only
in the top hypothesis.
This is an experimental feature and the accuracy of the time offset can
vary.
</pre>

<code>.google.protobuf.Duration end_time = 2;</code>
java-speech/proto-google-cloud-speech-v1/src/main/java/com/google/cloud/speech/v1/WordInfo.java