gwt-extras org.eclipse.jdt.core.javabuilder com.google.gdt.eclipse.core.webAppProjectValidator com.google.gwt.eclipse.core.gwtProjectValidator org.eclipse.m2e.core.maven2Builder org.eclipse.m2e.core.maven2Nature org.eclipse.jdt.core.javanature org.maven.ide.eclipse.maven2Nature com.google.gwt.eclipse.core.gwtNature