static ColumnMapperFactory of(Type type, ColumnMapper<?> mapper) {
        return (t, c) -> t.equals(type) ? Optional.of(mapper) : Optional.empty();
    }
Create a ColumnMapperFactory from a given {@link ColumnMapper} that
matches a single Type exactly.

@param type the type to match with equals.
@param mapper the mapper to return
@return the factory
core/src/main/java/org/jdbi/v3/core/mapper/ColumnMapperFactory.java