public com.google.protobuf.ByteString getSourceLanguageCodeBytes() {
      java.lang.Object ref = sourceLanguageCode_;
      if (ref instanceof String) {
        com.google.protobuf.ByteString b =
            com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);
        sourceLanguageCode_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
<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 The bytes for sourceLanguageCode.
java-translate/proto-google-cloud-translate-v3beta1/src/main/java/com/google/cloud/translate/v3beta1/BatchTranslateDocumentRequest.java