public com.google.protobuf.ByteString getCacheControlBytes() {
      java.lang.Object ref = cacheControl_;
      if (ref instanceof String) {
        com.google.protobuf.ByteString b =
            com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);
        cacheControl_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
<pre>
Optional. Updates objects Cache-Control fixed metadata. Unset values will
be
 ignored. Set empty values to clear the metadata.
 Additionally, the value for Custom-Time cannot decrease. Refer to
 documentation in
https://cloud.google.com/storage/docs/metadata#caching_data.
</pre>

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

@return The bytes for cacheControl.
java-storagebatchoperations/proto-google-cloud-storagebatchoperations-v1/src/main/java/com/google/cloud/storagebatchoperations/v1/PutMetadata.java