public Builder mergeFunctionCallingConfig(
        com.google.cloud.vertexai.api.FunctionCallingConfig value) {
      if (functionCallingConfigBuilder_ == null) {
        if (((bitField0_ & 0x00000001) != 0)
            && functionCallingConfig_ != null
            && functionCallingConfig_
                != com.google.cloud.vertexai.api.FunctionCallingConfig.getDefaultInstance()) {
          getFunctionCallingConfigBuilder().mergeFrom(value);
        } else {
          functionCallingConfig_ = value;
        }
      } else {
        functionCallingConfigBuilder_.mergeFrom(value);
      }
      if (functionCallingConfig_ != null) {
        bitField0_ |= 0x00000001;
        onChanged();
      }
      return this;
    }
<pre>
Optional. Function calling config.
</pre>

<code>
.google.cloud.vertexai.v1.FunctionCallingConfig function_calling_config = 1 [(.google.api.field_behavior) = OPTIONAL];
</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/ToolConfig.java