GSSAPI Authentication using a CNAME

Description
I am not able to connect to my PostgreSQL Server using the PostgreSQL JDBC Driver with GSSAPI when using the short name if the short name is a CNAME Record.
The fully qualified domain name does work when it is a CNAME.

For comparison, the psql client is able to connect using the short name when it is a CNAME.

JDBC Version
postgresql-42.2.16.jar

Dependancies
commons-cli-1.4

$ cat /opt/pgsql/conf/jaas.conf
pgjdbc {
com.sun.security.auth.module.Krb5LoginModule required
doNotPrompt=true
useTicketCache=true
renewTGT=true
debug=false
client=true;
};

Code Snippet
$ cat JDBCExample.java
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

import org.apache.commons.cli.CommandLine;
import org.apache.commons.cli.CommandLineParser;
import org.apache.commons.cli.DefaultParser;
import org.apache.commons.cli.Option;
import org.apache.commons.cli.Options;
import org.apache.commons.cli.ParseException;

public class JDBCExample {

public static void main(String[] args) throws ParseException {

Options options = new Options();

Option host = Option.builder()
.longOpt("host")
.argName("host")
.hasArg()
.desc("Name of the PostgreSQL Server.")
.build();

options.addOption(host);

Option db = Option.builder()
.longOpt("db")
.argName("db")
.hasArg()
.desc("Name of the PostgreSQL Database.")
.build();

options.addOption(db);

CommandLineParser parser = new DefaultParser();
CommandLine cmd = parser.parse( options, args);

String jdbcUrl = "jdbc:postgresql://" + cmd.getOptionValue("host") + ":5432/" + cmd.getOptionValue("db");

try (Connection conn = DriverManager.getConnection(jdbcUrl)) {

if (conn != null) {
System.out.println("Connected to the database!");
} else {
System.out.println("Failed to make connection!");
}

} catch (SQLException e) {
System.err.format("SQL State: %s\n%s", e.getSQLState(), e.getMessage());
} catch (Exception e) {
e.printStackTrace();
}

}
}

Compilation Steps
javac -cp .:postgresql-42.2.16.jar:commons-cli-1.4/commons-cli-1.4.jar JDBCExample.java

Results
$ java -Djava.security.krb5.realm=EXAMPLE.COM -Djava.security.krb5.kdc=EXAMPLE.COM -Djava.security.auth.login.config=/opt/pgsql/conf/jaas.conf -cp .:postgresql-42.2.16.jar:commons-cli-1.4/commons-cli-1.4.jar JDBCExample --host cname-hostname --db mydb
SQL State: 08006
GSS Authentication failed

$ java -Djava.security.krb5.realm=EXAMPLE.COM -Djava.security.krb5.kdc=EXAMPLE.COM -Djava.security.auth.login.config=/opt/pgsql/conf/jaas.conf -cp .:postgresql-42.2.16.jar:commons-cli-1.4/commons-cli-1.4.jar JDBCExample --host cname-hostname.example.com --db mydb
Connected to the database!

$ java -Djava.security.krb5.realm=EXAMPLE.COM -Djava.security.krb5.kdc=EXAMPLE.COM -Djava.security.auth.login.config=/opt/pgsql/conf/jaas.conf -cp .:postgresql-42.2.16.jar:commons-cli-1.4/commons-cli-1.4.jar JDBCExample --host hostname --db mydb
Connected to the database!

Jason Breitman