[531086] Unlikely org.eclipse.emf.codegen.ecore/plugin.properties entry

Also fix the message itself.
diff --git a/plugins/org.eclipse.emf.codegen.ecore/plugin.properties b/plugins/org.eclipse.emf.codegen.ecore/plugin.properties
index c483be8..639588a 100644
--- a/plugins/org.eclipse.emf.codegen.ecore/plugin.properties
+++ b/plugins/org.eclipse.emf.codegen.ecore/plugin.properties
@@ -112,4 +112,4 @@
 
 _UI_ValidGenModelAnnotationLocation_substitution = an Ecore named element
 _UI_InvalidAnnotationLabelEntryValue_diagnostic = The value ''{0}'' does not specify the name of an attribute of the annotation''s containing class
-_UI_ValidPropertyFactoryEditor_diagnostic =  There is registered property editor factory for ''{0}''
+_UI_ValidPropertyFactoryEditor_diagnostic =  There is no registered property editor factory for ''{0}''