public Builder mergeStartTime(com.google.protobuf.Duration value) {
      if (startTimeBuilder_ == null) {
        if (((bitField0_ & 0x00000001) != 0)
            && startTime_ != null
            && startTime_ != com.google.protobuf.Duration.getDefaultInstance()) {
          getStartTimeBuilder().mergeFrom(value);
        } else {
          startTime_ = value;
        }
      } else {
        startTimeBuilder_.mergeFrom(value);
      }
      if (startTime_ != null) {
        bitField0_ |= 0x00000001;
        onChanged();
      }
      return this;
    }
<pre>
Time offset relative to the beginning of the audio, and
corresponding to the start 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 start_time = 1;</code>
java-video-intelligence/proto-google-cloud-video-intelligence-v1p3beta1/src/main/java/com/google/cloud/videointelligence/v1p3beta1/WordInfo.java