public com.google.protobuf.ByteString getApiVersionBytes() {
      java.lang.Object ref = apiVersion_;
      if (ref instanceof String) {
        com.google.protobuf.ByteString b =
            com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);
        apiVersion_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
<pre>
API version.
</pre>

<code>string api_version = 7;</code>

@return The bytes for apiVersion.
java-tpu/proto-google-cloud-tpu-v1/src/main/java/com/google/cloud/tpu/v1/OperationMetadata.java