Access denied for Sonar database - sonarqube

Question

I encounter an 'Access denied' error when connecting to the Sonar database. Below the trace:
[workspace] $ /var/lib/jenkins/tools/hudson.plugins.sonar.SonarRunnerInstallation/Sonar/bin/sonar-runner -Dsonar.jdbc.driver=com.mysql.jdbc.Driver -Dsonar.jdbc.url=jdbc:mysql://tridev002.xxxxx.net:3306/sonar ******** ******** -Dsonar.host.url=http://tridev002.xxxx.net:9000/ ******** ******** "-Dsonar.projectBaseDir=/var/lib/jenkins/jobs/Test Sonar/workspace"
SonarQube Runner 2.4
Java 1.7.0_72 Oracle Corporation (64-bit)
Linux 3.2.0-4-amd64 amd64
INFO: Runner configuration file: /var/lib/jenkins/tools/hudson.plugins.sonar.SonarRunnerInstallation/Sonar/conf/sonar-runner.properties
INFO: Project configuration file: NONE
INFO: Default locale: "en_US", source code encoding: "UTF-8" (analysis is platform dependent)
INFO: Work directory: /var/lib/jenkins/jobs/Test Sonar/workspace/.sonar
INFO: SonarQube Server 4.5.1
13:44:54.656 INFO - Load global referentials...
13:44:54.825 INFO - Load global referentials done: 173 ms
13:44:54.833 INFO - User cache: /var/lib/jenkins/.sonar/cache
13:44:54.841 INFO - Install plugins
13:44:54.920 INFO - Install JDBC driver
13:44:54.926 INFO - Create JDBC datasource for jdbc:mysql://tridev002.xxxxx.net:3306/sonar
INFO: ------------------------------------------------------------------------
INFO: EXECUTION FAILURE
INFO: ------------------------------------------------------------------------
Total time: 1.494s
Final Memory: 8M/241M
INFO: ------------------------------------------------------------------------
ERROR: Error during Sonar runner execution
ERROR: Unable to execute Sonar
ERROR: Caused by: Fail to connect to database
ERROR: Caused by: Cannot create PoolableConnectionFactory (Access denied for user 'jenkins-sonar'#'tridev002.xxxxx.net' (using password: YES))
ERROR: Caused by: Access denied for user 'jenkins- sonar'#'tridev002.xxxxx.net' (using password: YES)
ERROR:
ERROR: To see the full stack trace of the errors, re-run SonarQube Runner with the -e switch.
ERROR: Re-run SonarQube Runner using the -X switch to enable full debug logging.
Build step 'Invoke Standalone Sonar Analysis' marked build as failure
In the Jenkins configuration the Database URL, Database login en Database password are set correctly. With this URL and credentials it is possible to log in via a mysql command line client and we can view the sonar database tables.
We also checked the permissions of the database user and these are set correctly.
We checked the sonar.properties file and everything is commented out.
If we add sonar.jdbc.username and sonar.jdbc.password to the project properties, the connection with the database is successfull. But the password is in plain text then, which is unadvisable.
Does anyone know why the credentials of the system configuration is not used? And what is the solution? Is this a bug in SonarQube?