presto-main/src/main/java/io/prestosql/operator/scalar/MapValues.java/MapValues/getValues
class MapValues:    @TypeParameter("K")
    @TypeParameter("V")
    @SqlType("array(V)")
    public static Block getValues(
            @TypeParameter("V") Type valueType,
            @SqlType("map(K,V)") Block block)
    {
        BlockBuilder blockBuilder = valueType.createBlockBuilder(null, block.getPositionCount() / 2);
        for (int i = 0; i < block.getPositionCount(); i += 2) {
            valueType.appendTo(block, i + 1, blockBuilder);
        }
        return blockBuilder.build();
    }