@Nonnull
    public static <K, V> BatchSource<Entry<K, V>> map(@Nonnull String mapName) {
        return batchFromProcessor("mapSource(" + mapName + ')', readMapP(mapName));
    }
@Test
    public void mapWithFilterAndProjection_byName() {
        // Given
        List<Integer> input = sequence(itemCount);
        putToBatchSrcMap(input);

        // When
        BatchSource<Object> source = Sources.map(srcName, truePredicate(), singleAttribute("value"));

        // Then
        p.readFrom(source).writeTo(sink);
        execute();
        assertEquals(toBag(input), sinkToBag());
    }