public Builder clearSourceLanguageCode() {
      sourceLanguageCode_ = getDefaultInstance().getSourceLanguageCode();
      bitField0_ = (bitField0_ & ~0x00000002);
      onChanged();
      return this;
    }
<pre>
Required. The BCP-47 language code of the input document if known, for
example, "en-US" or "sr-Latn". Supported language codes are listed in
[Language Support](https://cloud.google.com/translate/docs/languages).
</pre>

<code>string source_language_code = 2 [(.google.api.field_behavior) = REQUIRED];</code>

@return This builder for chaining.
java-translate/proto-google-cloud-translate-v3beta1/src/main/java/com/google/cloud/translate/v3beta1/BatchTranslateDocumentRequest.java