Bug 175742 [Markers] contributed marker resolutions only showing first contribution
Debug is trying to add a marker resolution for a quick fix to repair deprecated JRE variables on the build path. When we contribute our resolution generator for org.eclipse.jdt.core.buildpath_problem marker types with a DEPRECATED_VARIABLE id attribute, we find that our resolution is always over-written by the junit generator. It seems that the MarkerHelpRegistry does not allow more than one generator per query result (in our case DEPRECATED_VARIABLE is the query result, same with junit's contribution). I would expect that you could have more than one quickfix for a given issue (in this case what to do about deprecated build path variables).
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/registry/MarkerHelpRegistry.java
/* (non-Javadoc)
         * Method declared on Object.
         */
        public boolean equals(Object o) {
            if (!(o instanceof QueryComparator)) {
				return false;
			}
            return true;