Bug 8476 JAR Packager: Make main class field editable
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/jarpackager/JarManifestWizardPage.java
}			
				IResource resource= findResource(location);
				if (resource != null && resource.getType() != IResource.FILE) {
					setErrorMessage(JarPackagerMessages.getString("JarManifestWizardPage.error.manifestMustNotBeExistingContainer")); 
					return false;
				}
				resource= findResource(location.removeLastSegments(1));
				if (resource == null || resource.getType() == IResource.FILE) {
					setErrorMessage(JarPackagerMessages.getString("JarManifestWizardPage.error.manifestContainerDoesNotExist")); 
					return false;
				}
			}
		}
		if (!fJarPackage.isManifestGenerated() && !fJarPackage.doesManifestExist()) {
			if (fJarPackage.getManifestLocation().toString().length() == 0)
					incompleteButNotAnError= true;
			else {			
				setErrorMessage(JarPackagerMessages.getString("JarManifestWizardPage.error.invalidManifestFile")); 
				return false;
			}
		}
		if (fJarPackage.isJarSealed()
				&& !fJarPackage.getPackagesForSelectedResources().containsAll(Arrays.asList(fJarPackage.getPackagesToUnseal()))) {
			setErrorMessage(JarPackagerMessages.getString("JarManifestWizardPage.error.unsealedPackagesNotInSelection")); 
			return false;
		}
		if (!fJarPackage.isJarSealed()
				&& !fJarPackage.getPackagesForSelectedResources().containsAll(Arrays.asList(fJarPackage.getPackagesToSeal()))) {
			setErrorMessage(JarPackagerMessages.getString("JarManifestWizardPage.error.sealedPackagesNotInSelection")); 
			return false;