public static ConfigDef appendConfigTo(ConfigDef configDef) {
        return configDef
                .define(
                        FieldSyntaxVersion.FIELD_SYNTAX_VERSION_CONFIG,
                        ConfigDef.Type.STRING,
                        FieldSyntaxVersion.FIELD_SYNTAX_VERSION_DEFAULT_VALUE,
                        ConfigDef.CaseInsensitiveValidString.in(Utils.enumOptions(FieldSyntaxVersion.class)),
                        ConfigDef.Importance.HIGH,
                        FieldSyntaxVersion.FIELD_SYNTAX_VERSION_DOC);
    }
Extend existing config definition by adding field syntax version.
To be used by transforms supporting nested fields.

@param configDef exiting config definition
@return config definition including field syntax version definition
connect/transforms/src/main/java/org/apache/kafka/connect/transforms/field/FieldSyntaxVersion.java