public Builder clearApiVersion() {
      apiVersion_ = getDefaultInstance().getApiVersion();
      bitField0_ = (bitField0_ & ~0x00000010);
      onChanged();
      return this;
    }
<pre>
API version used to start the operation.
</pre>

<code>string api_version = 5;</code>

@return This builder for chaining.
java-workflows/proto-google-cloud-workflows-v1/src/main/java/com/google/cloud/workflows/v1/OperationMetadata.java