So I figured out what was wrong.
I tried to use the ldap.user.roles.ctx instead of ldap.role.ctx and the error message is gone.
Looking in the class implementation I saw at line 236: https://github.com/droolsjbpm/jbpm/blob/5.4.x/jbpm-human-task/jbpm-human-task-core/src/main/java/org/jbpm/task/identity/LDAPUserGroupCallbackImpl.java
{code}
String roleContext = this.config.getProperty(USER_ROLES_CTX, ROLE_CTX);
{code}
It tries to get the value for the key USER_ROLES_CTX, if this key is not in the property list, then it uses ROLE_CTX as default VALUE. This means it doesn't look for ROLE_CTX in the property list.
And that's why I get such an error message.
This is a bug should I open a jira?!
Regards,
Eduardo