```
from employees | keep * | mv_expand first_name
```

throws UnresolvedException:

```
org.elasticsearch.xpack.ql.capabilities.UnresolvedException: Invalid call to attribute on an unresolved object ?*
        at org.elasticsearch.xpack.ql.expression.UnresolvedNamedExpression.toAttribute(UnresolvedNamedExpression.java:44)
        at org.elasticsearch.xpack.ql.expression.Expressions.asAttributes(Expressions.java:40)
        at org.elasticsearch.xpack.ql.plan.logical.Project.output(Project.java:62)
        at org.elasticsearch.xpack.esql.plan.logical.MvExpand.<init>(MvExpand.java:31)
        at org.elasticsearch.xpack.esql.parser.LogicalPlanBuilder.lambda$visitMvExpandCommand$3(LogicalPlanBuilder.java:154)
        at org.elasticsearch.xpack.esql.parser.LogicalPlanBuilder.visitCompositeQuery(LogicalPlanBuilder.java:89)
        at org.elasticsearch.xpack.esql.parser.LogicalPlanBuilder.visitCompositeQuery(LogicalPlanBuilder.java:66)
        at org.elasticsearch.xpack.esql.parser.EsqlBaseParser$CompositeQueryContext.accept(EsqlBaseParser.java:232)
        at org.elasticsearch.xpack.ql.parser.ParserUtils.typedParsing(ParserUtils.java:51)
        at org.elasticsearch.xpack.esql.parser.LogicalPlanBuilder.plan(LogicalPlanBuilder.java:73)
        at org.elasticsearch.xpack.esql.parser.LogicalPlanBuilder.visitSingleStatement(LogicalPlanBuilder.java:82)
        at org.elasticsearch.xpack.esql.parser.LogicalPlanBuilder.visitSingleStatement(LogicalPlanBuilder.java:66)
        at org.elasticsearch.xpack.esql.parser.EsqlBaseParser$SingleStatementContext.accept(EsqlBaseParser.java:169)
```

The problem is that MV_EXPAND tries to pre-calculate the output too early, when the resolution did not happen yet.
x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/parser/StatementParserTests.java
);
    }
    public void testMvExpand() {
        LogicalPlan cmd = processingCommand("mv_expand a");
        assertEquals(MvExpand.class, cmd.getClass());
        MvExpand expand = (MvExpand) cmd;
        assertThat(expand.target(), equalTo(attribute("a")));
    }
    public void testUsageOfProject() {
        processingCommand("project a");
        assertWarnings("PROJECT command is no longer supported, please use KEEP instead");
    }
    public void testInputParams() {
        LogicalPlan stm = statement(
            "row x = ?, y = ?, a = ?, b = ?, c = ?",
            List.of(
                new TypedParamValue("integer", 1),
                new TypedParamValue("keyword", "2"),
                new TypedParamValue("date_period", "2 days"),
                new TypedParamValue("time_duration", "4 hours"),
                new TypedParamValue("version", "1.2.3")
            )
        );
        assertThat(stm, instanceOf(Row.class));
        Row row = (Row) stm;
        assertThat(row.fields().size(), is(5));
        NamedExpression field = row.fields().get(0);
        assertThat(field.name(), is("x"));
        assertThat(field, instanceOf(Alias.class));
        Alias alias = (Alias) field;