PostgresPlus returns column names enclosed in quotes if the field was enclosed in quotes when the index was created; other DBs apparently don't return quotes column names. Hibernate assumes that the column names are not quoted, resulting the excepton:
"org.hibernate.boot.model.naming.IllegalIdentifierException: Identifier text should not contain quote markers (` or ")"
This is reproduced by SchemaUpdateTest.testSchemaUpdateAndValidation on PostgresPlus.
Fixed in 5.1 branch as well.