IEditableSupport editableSupport = support.getEditable();
// prepare editable source
IEditableSource editableSource = NlsTestUtils.createEmptyEditable("test.client.MyConstants");
editableSource.setKeyGeneratorStrategy(GwtSource.GWT_KEY_GENERATOR);
// prepare parameters
SourceParameters parameters = new SourceParameters();
IJavaProject javaProject = m_lastEditor.getJavaProject();
{
parameters.m_constant = new SourceClassParameters();
SourceClassParameters constant = parameters.m_constant;
constant.m_sourceFolder = javaProject.findPackageFragmentRoot(new Path("/TestProject/src"));