public Builder mergeUsageMetadata(
        com.google.cloud.vertexai.api.GenerateContentResponse.UsageMetadata value) {
      if (usageMetadataBuilder_ == null) {
        if (((bitField0_ & 0x00000020) != 0)
            && usageMetadata_ != null
            && usageMetadata_
                != com.google.cloud.vertexai.api.GenerateContentResponse.UsageMetadata
                    .getDefaultInstance()) {
          getUsageMetadataBuilder().mergeFrom(value);
        } else {
          usageMetadata_ = value;
        }
      } else {
        usageMetadataBuilder_.mergeFrom(value);
      }
      if (usageMetadata_ != null) {
        bitField0_ |= 0x00000020;
        onChanged();
      }
      return this;
    }
<pre>
Usage metadata about the response(s).
</pre>

<code>.google.cloud.vertexai.v1.GenerateContentResponse.UsageMetadata usage_metadata = 4;
</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/GenerateContentResponse.java