@java.lang.Override
      public final Builder setUnknownFields(
          final com.google.protobuf.UnknownFieldSet unknownFields) {
        return super.setUnknownFields(unknownFields);
      }
<pre>
Required. The zero-based index of the track in the input file.
</pre>

<code>int32 input_track = 3 [(.google.api.field_behavior) = REQUIRED];</code>

@return This builder for chaining.
java-video-transcoder/proto-google-cloud-video-transcoder-v1/src/main/java/com/google/cloud/video/transcoder/v1/TextStream.java