private Set<LessSource> resolveImportsAndReferences(StyleSheet less, LessSource source) {
ImportsAndScopeSolver solver = new ImportsAndScopeSolver(problemsHandler, configuration);
IScope scope = solver.buildImportsAndScope(less, source);
Set<LessSource> importedSources = solver.getImportedSources();
ReferencesSolver referencesSolver = new ReferencesSolver(problemsHandler, configuration);
referencesSolver.solveReferences(less, scope);
// Warning at this point: ast changed, but the scope did not changed its structure. The scope stopped to be useful.
return importedSources;
}