public com.google.protobuf.ByteString getFilterBytes() {
      java.lang.Object ref = filter_;
      if (ref instanceof String) {
        com.google.protobuf.ByteString b =
            com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);
        filter_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
<pre>
Optional. Filters applied to the [Executions.ListExecutions] results.
The following fields are supported for filtering:
executionID, state, startTime, endTime, duration, workflowRevisionID,
stepName, and label.
</pre>

<code>string filter = 5 [(.google.api.field_behavior) = OPTIONAL];</code>

@return The bytes for filter.
java-workflow-executions/proto-google-cloud-workflow-executions-v1/src/main/java/com/google/cloud/workflows/executions/v1/ListExecutionsRequest.java