@Override public String source(String templateId) { Checker.checkArgumentNotEmpty(templateId); String mustacheSource = engine.getMustacheSource(templateId); if (mustacheSource == null) { throw new MustacheException( MustacheProblem.RENDER_INVALID_PARTIAL_KEY, "No mustache template found for the given key: %s %s", templateId, segment.getOrigin()); } return mustacheSource; }