@java.lang.Override
        public void writeTo(com.google.protobuf.CodedOutputStream output)
            throws java.io.IOException {
          if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(targetAudienceClientId_)) {
            com.google.protobuf.GeneratedMessageV3.writeString(output, 1, targetAudienceClientId_);
          }
          getUnknownFields().writeTo(output);
        }
<pre>
Required. Describes OAuth2 client id of resources protected by
Identity-Aware-Proxy (IAP).
</pre>

<code>string target_audience_client_id = 1 [(.google.api.field_behavior) = REQUIRED];
</code>

@return The bytes for targetAudienceClientId.
java-websecurityscanner/proto-google-cloud-websecurityscanner-v1/src/main/java/com/google/cloud/websecurityscanner/v1/ScanConfig.java