public IssueFilter addLabel(Label label) {
        if (label == null) {
            return this;
        }
        if (labels == null) {
            labels = new ArrayList<>();
        }
        labels.add(label);
        return this;
    }
Add label to filter

@param label
@return this filter
app/src/main/java/com/github/pockethub/android/core/issue/IssueFilter.java