@java.lang.Override
  public void writeTo(com.google.protobuf.CodedOutputStream output) throws java.io.IOException {
    if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(parent_)) {
      com.google.protobuf.GeneratedMessageV3.writeString(output, 1, parent_);
    }
    if (pageSize_ != 0) {
      output.writeInt32(2, pageSize_);
    }
    if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(pageToken_)) {
      com.google.protobuf.GeneratedMessageV3.writeString(output, 3, pageToken_);
    }
    if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(filter_)) {
      com.google.protobuf.GeneratedMessageV3.writeString(output, 4, filter_);
    }
    getUnknownFields().writeTo(output);
  }
<pre>
Optional. An expression for filtering the results of the request.
Filter is not supported yet.
</pre>

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

@return The bytes for filter.
java-translate/proto-google-cloud-translate-v3/src/main/java/com/google/cloud/translate/v3/ListAdaptiveMtDatasetsRequest.java