private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.vmmigration.v1.AwsSourceDetails,
            com.google.cloud.vmmigration.v1.AwsSourceDetails.Builder,
            com.google.cloud.vmmigration.v1.AwsSourceDetailsOrBuilder>
        getAwsFieldBuilder() {
      if (awsBuilder_ == null) {
        if (!(sourceDetailsCase_ == 12)) {
          sourceDetails_ = com.google.cloud.vmmigration.v1.AwsSourceDetails.getDefaultInstance();
        }
        awsBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.vmmigration.v1.AwsSourceDetails,
                com.google.cloud.vmmigration.v1.AwsSourceDetails.Builder,
                com.google.cloud.vmmigration.v1.AwsSourceDetailsOrBuilder>(
                (com.google.cloud.vmmigration.v1.AwsSourceDetails) sourceDetails_,
                getParentForChildren(),
                isClean());
        sourceDetails_ = null;
      }
      sourceDetailsCase_ = 12;
      onChanged();
      return awsBuilder_;
    }
<pre>
AWS type source details.
</pre>

<code>.google.cloud.vmmigration.v1.AwsSourceDetails aws = 12;</code>
java-vmmigration/proto-google-cloud-vmmigration-v1/src/main/java/com/google/cloud/vmmigration/v1/Source.java