Abstract method cannot be accessed directly

The refactoring failed and caused the following errors:

• abstract method getName() in fr.alma.gtd.server.core.AbstractTask cannot be accessed directly
• abstract method getPriority() in fr.alma.gtd.server.core.AbstractTask cannot be accessed directly
• abstract method getEffortRate() in fr.alma.gtd.server.core.AbstractTask cannot be accessed directly
• attempting to assign weaker access privileges

Correct this bug without break anything.