@java.lang.Override
  public void writeTo(com.google.protobuf.CodedOutputStream output) throws java.io.IOException {
    if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(asset_)) {
      com.google.protobuf.GeneratedMessageV3.writeString(output, 1, asset_);
    }
    if (((bitField0_ & 0x00000001) != 0)) {
      output.writeMessage(2, getResolution());
    }
    if (((bitField0_ & 0x00000002) != 0)) {
      output.writeMessage(3, getPosition());
    }
    if (java.lang.Double.doubleToRawLongBits(opacity_) != 0) {
      output.writeDouble(4, opacity_);
    }
    getUnknownFields().writeTo(output);
  }
<pre>
Optional. Target image opacity. Valid values are from `1.0` (solid,
default) to `0.0` (transparent), exclusive. Set this to a value greater
than `0.0`.
</pre>

<code>double opacity = 4 [(.google.api.field_behavior) = OPTIONAL];</code>

@return The opacity.
java-video-live-stream/proto-google-cloud-live-stream-v1/src/main/java/com/google/cloud/video/livestream/v1/StaticOverlay.java