public boolean hasMetadata() {
      return ((bitField0_ & 0x00000004) != 0);
    }
<pre>
Input only. This field is for users to attach user managed metadata.
</pre>

<code>.google.protobuf.Struct metadata = 3 [(.google.api.field_behavior) = INPUT_ONLY];
</code>

@return Whether the metadata field is set.
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/PacketHeader.java