public static String getMapFieldKeyType(Field field) {
        FieldType type = field.getType();
        if (!(type instanceof Message)) {
            throw new IllegalArgumentException(field.toString());
        }
        Message entryType = (Message) type;
        ScalarFieldType keyType = (ScalarFieldType) entryType.getField(MAP_ENTRY_KEY).getType();
        return ScalarFieldTypeUtil.getWrapperType(keyType);
    }
public static String getMapFieldKeyType ( Field field ) { FieldType type = field . getType ( ) ; if ( ! ( type instanceof Message ) ) { throw new IllegalArgumentException ( field . toString ( ) ) ; } Message entryType = ( Message ) type ; ScalarFieldType keyType = ( ScalarFieldType ) entryType . getField ( MAP_ENTRY_KEY ) . getType ( ) ; return ScalarFieldTypeUtil . getWrapperType ( keyType ) ; }
Returns map field key type name.