private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.visionai.v1.ServerMetadata,
            com.google.cloud.visionai.v1.ServerMetadata.Builder,
            com.google.cloud.visionai.v1.ServerMetadataOrBuilder>
        getServerMetadataFieldBuilder() {
      if (serverMetadataBuilder_ == null) {
        serverMetadataBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.visionai.v1.ServerMetadata,
                com.google.cloud.visionai.v1.ServerMetadata.Builder,
                com.google.cloud.visionai.v1.ServerMetadataOrBuilder>(
                getServerMetadata(), getParentForChildren(), isClean());
        serverMetadata_ = null;
      }
      return serverMetadataBuilder_;
    }
<pre>
Output only. Metadata that the server appends to each packet before sending
it to receivers. You don't need to set a value for this field when sending
packets.
</pre>

<code>
.google.cloud.visionai.v1.ServerMetadata server_metadata = 4 [(.google.api.field_behavior) = OUTPUT_ONLY];
</code>
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/PacketHeader.java