"org.guvnor.common.services.builder.Builder" at the end of build() method swallow Exception:
~~~
for ( final String packageName : kieModuleMetaData.getPackages() ) {
for ( final String className : kieModuleMetaData.getClasses( packageName ) ) {
final String fullyQualifiedClassName = packageName + "." + className;
try {
final Class clazz = kieModuleMetaData.getClass( packageName,
className );
final TypeSource typeSource = getClassSource( kieModuleMetaData,
clazz );
if ( TypeSource.JAVA_DEPENDENCY == typeSource )

{ verifyExternalClass( clazz ); }

} catch ( NoClassDefFoundError e )

{ final String msg = MessageFormat.format( ERROR_EXTERNAL_CLASS_VERIFICATON, fullyQualifiedClassName ); logger.warn( msg ); results.addBuildMessage( makeWarningMessage( msg ) ); }

catch ( Throwable e )

{ final String msg = MessageFormat.format( ERROR_EXTERNAL_CLASS_VERIFICATON, fullyQualifiedClassName ); logger.error( msg ); results.addBuildMessage( makeErrorMessage( msg ) ); }

}
}
~~~

Note that NoClassDefFoundError be swallowed, the output didn't contain No exist class.