generateOneofAccessors method
Implementation
void generateOneofAccessors(IndentingWriter out, OneofNames oneof) {
out.println();
out.println('${oneof.oneofEnumName} ${oneof.whichOneofMethodName}() '
'=> ${oneof.byTagMapName}[\$_whichOneof(${oneof.index})]!;');
out.println('void ${oneof.clearMethodName}() '
'=> clearField(\$_whichOneof(${oneof.index}));');
}