Column metadata has incorrect length/scale for domain types

[Naros]

I'm submitting a ...

• bug report
• feature request

Describe the issue
When iterating the result-set returned from DatabaseMetaData#getColumns the length and scale of a column is being reported incorrectly for columns that are based on domain types where the type modifiers are embedded in the type definition.

For example, when executing the following SQL:

CREATE DOMAIN varbit2 AS varbit(3);
CREATE TABLE test_table (pk SERIAL, value varbit2 NOT NULL, PRIMARY KEY(pk));
INSERT INTO test_table (value) values (B'101');

In this use case, I would expect that the length would have been specified as 3 but instead the value returned from the result-set is 2147483647 which does not appropriately describe the column's size constraints.

Driver Version?
42.2.8

Java Version?
8+

OS Version?
Fedora 30

PostgreSQL Version?
PG10+

To Reproduce
Steps to reproduce the behaviour:
Execute the specified SQL statements above to create the domain type varbit2 and then fetch the column metadata for table test_table.

Expected behaviour
Expected length to be 3 rather than 2147483647.

[davecramer]

fixed by #1605