Bug 205049 Other plug-ins should be able to define default content generator
Currently only the content generator can define which plug-ins it can be the default for - we need a way for plug-ins to refer back to the marker support for thier own generator.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/views/markers/internal/MarkerSupportRegistry.java
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IExtension;
import org.eclipse.core.runtime.IExtensionPoint;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Platform;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.dynamichelpers.ExtensionTracker;
import org.eclipse.core.runtime.dynamichelpers.IExtensionChangeHandler;
import org.eclipse.core.runtime.dynamichelpers.IExtensionTracker;
import org.eclipse.osgi.util.NLS;
import org.eclipse.ui.IPerspectiveDescriptor;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.internal.ide.IDEWorkbenchPlugin;
import org.eclipse.ui.internal.provisional.views.markers.MarkerContentGenerator;
import org.eclipse.ui.internal.provisional.views.markers.api.MarkerField;
import org.eclipse.ui.internal.provisional.views.markers.api.MarkerSupportConstants;
import org.eclipse.ui.statushandlers.StatusManager;
/**
 * The ProblemFilterRegistryReader is the registry reader for declarative
 * problem filters. See the org.eclipse.ui.markerSupport extension point.
 * 
 * @since 3.2
 * 
 */
public class MarkerSupportRegistry implements IExtensionChangeHandler {
	private static final String DESCRIPTION = "onDescription"; 
	private static final String ENABLED = "enabled"; 
	private static final Object ERROR = "ERROR";
	private static final Object INFO = "INFO";