presto-main/src/main/java/io/prestosql/operator/scalar/ArrayFunctions.java/ArrayFunctions/arrayConstructor
class ArrayFunctions:    @ScalarFunction(hidden = true)
    @SqlType("array(unknown)")
    public static Block arrayConstructor()
    {
        BlockBuilder blockBuilder = new ArrayType(UNKNOWN).createBlockBuilder(null, 0);
        return blockBuilder.build();
    }