```
ROW a="b c d"
| DISSECT a "%{b} %{} %{d}"
```
returns

```
       a       |       b       |               |       d       
---------------+---------------+---------------+---------------
b c d          |b              |null           |d 
```

it should ignore the empty pattern instead, and only return `a, b, d`
x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/parser/StatementParserTests.java
assertThat(((UnresolvedAttribute) add.right()).name(), equalTo("b"));
        order = orderBy.order().get(1);
        assertThat(order.direction(), equalTo(Order.OrderDirection.DESC));
        assertThat(order.nullsPosition(), equalTo(Order.NullsPosition.LAST));
        assertThat(order.child(), instanceOf(UnresolvedAttribute.class));
        assertThat(((UnresolvedAttribute) order.child()).name(), equalTo("x"));
        assertThat(orderBy.children().size(), equalTo(1));
        assertThat(orderBy.children().get(0), instanceOf(Filter.class));
        assertThat(orderBy.children().get(0).children().size(), equalTo(1));
        assertThat(orderBy.children().get(0).children().get(0), instanceOf(EsqlUnresolvedRelation.class));
    }
    public void testSubquery() {
        assertEquals(new Explain(EMPTY, PROCESSING_CMD_INPUT), statement("explain [ row a = 1 ]"));
    }
    public void testSubqueryWithPipe() {
        assertEquals(
            new Limit(EMPTY, integer(10), new Explain(EMPTY, PROCESSING_CMD_INPUT)),
            statement("explain [ row a = 1 ] | limit 10")
        );
    }
    public void testNestedSubqueries() {
        assertEquals(
            new Limit(
                EMPTY,
                integer(10),
                new Explain(EMPTY, new Limit(EMPTY, integer(5), new Explain(EMPTY, new Limit(EMPTY, integer(1), PROCESSING_CMD_INPUT))))
            ),
            statement("explain [ explain [ row a = 1 | limit 1 ] | limit 5 ] | limit 10")
        );
    }