private void ensureRuntimeVersionsIsMutable() {
      if (!((bitField0_ & 0x00000001) != 0)) {
        runtimeVersions_ =
            new java.util.ArrayList<com.google.cloud.tpu.v2.RuntimeVersion>(runtimeVersions_);
        bitField0_ |= 0x00000001;
      }
    }
<pre>
Response for
[ListRuntimeVersions][google.cloud.tpu.v2.Tpu.ListRuntimeVersions].
</pre>

Protobuf type {@code google.cloud.tpu.v2.ListRuntimeVersionsResponse}
java-tpu/proto-google-cloud-tpu-v2/src/main/java/com/google/cloud/tpu/v2/ListRuntimeVersionsResponse.java