Commented by: Francois Le Rolland (flerolland)

Same behavior with getPrimarykeys method.
This troubleshouting comes from the AbsractDatabaseMetaData.Clause class.
The contructor estimate that the table name with an underscore contains a wildcard and add a "%" at the end of the search string.
A good fix may be another constructor with a third parameter :
public Clause (String columnName, String pattern, boolean skipWildcards) {
...
}

Commented by: Roman Rokytskyy (rrokytskyy)

the issue was caused by a bug made while fixing the uppercasing issue there.