spyglass/src/main/java/com/linkedin/android/spyglass/ui/MentionsEditText.java
private void sendBeforeTextChanged(CharSequence text, int start, int before, int after) {
        final List<TextWatcher> list = mExternalTextWatchers;
        final int count = list.size();
        for (int i = 0; i < count; i++) {
            TextWatcher watcher = list.get(i);
            if (watcher != this) {
                watcher.beforeTextChanged(text, start, before, after);
            }
        }
    }
private void sendBeforeTextChanged(CharSequence text, int start, int before, int after) {
        final List<TextWatcher> list = mExternalTextWatchers;
        final int count = list.size();
        for (int i = 0; i < count; i++) {
            TextWatcher watcher = list.get(i);
            if (watcher != this) {
                watcher.beforeTextChanged(text, start, before, after);
            }
        }
    }
Notify external text watchers that the text is about to change.
See {@link TextWatcher#beforeTextChanged(CharSequence, int, int, int)}.