Static method call from Eclipse Plugin: InjectionException - eclipse

Question

I have 2 plugin projects - generator.ui and generator.core.
The generator.ui depends on generator.core plugin for processes and data manipulation. However wherever there is an API call on generator.core (through static method invocation), I get an exception mentioned below:
org.eclipse.e4.core.di.InjectionException: java.lang.NoClassDefFoundError: de/upb/crc901/serge/generator/Generator
at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:63)
at org.eclipse.e4.core.internal.di.InjectorImpl.invokeUsingClass(InjectorImpl.java:243)
at org.eclipse.e4.core.internal.di.InjectorImpl.invoke(InjectorImpl.java:224)
at org.eclipse.e4.core.contexts.ContextInjectionFactory.invoke(ContextInjectionFactory.java:132)
at org.eclipse.e4.core.commands.internal.HandlerServiceHandler.execute(HandlerServiceHandler.java:167)
at org.eclipse.core.commands.Command.executeWithChecks(Command.java:499)
at org.eclipse.core.commands.ParameterizedCommand.executeWithChecks(ParameterizedCommand.java:508)
at org.eclipse.e4.core.commands.internal.HandlerServiceImpl.executeHandler(HandlerServiceImpl.java:213)
at org.eclipse.e4.ui.workbench.renderers.swt.HandledContributionItem.executeItem(HandledContributionItem.java:850).........
Caused by: java.lang.ClassNotFoundException: de.upb.crc901.serge.generator.Generator cannot be found by de.upb.crc901.serge.ui_1.0.0.qualifier
at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:501)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:421)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:412)
at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107)
at java.lang.ClassLoader.loadClass(Unknown Source)
Now this NoClassDefFoundError always comes for the class which contains static method for object creation as the design pattern followed is "Singleton".
Any help would be greatly appreciated.
Here is the code, From the UI plugin; the configuration hub class:
public class ConfigurationHub implements IConfigurationHub {
private IGenerator generator;
private static IConfigurationHub configurationHub;
/*
* Constructor private to make Singleton
*/
private ConfigurationHub() {
generator = GeneratorFactory.createGenerator(Generator.class);
}
public static synchronized IConfigurationHub getInstance() {
if(null == configurationHub) {
configurationHub = new ConfigurationHub();
}
return configurationHub;
}
}
The GeneratorFactory class is in Generator plugin:
public class GeneratorFactory {
private GeneratorFactory() {}
public static <T extends IGenerator> T createGenerator(Class<T> type) {
try {
return (T) type.newInstance();
} catch (InstantiationException e) {
e.printStackTrace();
return null;
} catch (IllegalAccessException e) {
e.printStackTrace();
return null;
}
}
}
Regards,
Sid