pgjdbc does not enforce requireAuth when the value excludes every authentication method

pgjdbc, the PostgreSQL JDBC Driver, versions 42.7.11 through 42.7.13 enforce no restriction when the requireAuth connection property excludes all six authentication methods the driver knows, for example requireAuth=!password,!md5,!gss,!sspi,!scram-sha-256,!none. The driver then accepts any method the server asks for, including cleartext password authentication. A value without a method in it, such as requireAuth=, (a single comma), is affected the same way. An attacker positioned between the application and its server can ask for cleartext password authentication and receive the database password. A positive list such as requireAuth=scram-sha-256, and a partial exclusion such as requireAuth=!password,!md5, are enforced correctly. The property has no default value, so a deployment that does not set it is not affected. 42.7.14 fixes the problem: such a connection is refused with SQLState 08004, and a value without a method in it is rejected as invalid.