SELECT COALESCE(...) isn't inferred as non-nullable field

[damccorm]

In Calcite, Coalesce is described as:

ReturnTypes.cascade(ReturnTypes.LEAST_RESTRICTIVE,
            SqlTypeTransforms.LEAST_NULLABLE)

However, giving non-null constant as an argument doesn't result in a non-nullable expression:

    Schema inputSchema = Schema.of(
        Schema.Field.of("name", Schema.FieldType.STRING.withNullable(true)));


   PCollection<Row> input = p.apply(Create.of(ImmutableList.<Row>of())
        .withCoder(SchemaCoder.of(inputSchema)));


   Schema outputSchema = input
        .apply(SqlTransform.query("SELECT COALESCE(name, 'unknown')
as name FROM PCOLLECTION"))
        .getSchema();

    assertEquals(
        Schema.builder().addStringField("name").build(),

       outputSchema);

Not sure if it's a problem in Calcite or Beam SQL.

There are no other functions that can be used to produce a non-nullable field.

Imported from Jira BEAM-7610. Original Jira may contain additional context.
Reported by: kanterov.

[judahrand]

This was fixed in Calcite 1.22.0 but I'm still having this issue in Beam 2.39.