question: public final void addHelperText ( @ NonNull final CharSequence helperText ) { ensureNotNull ( helperText , "The helper text may not be null" ) ; ensureNotEmpty ( helperText , "The helper text may not be empty" ) ; if ( ! helperTexts . contains ( helperText ) ) { helperTexts . add ( helperText ) ; verifyPasswordStrength ( ) ; } }
target:  Adds a new helper text, which should be shown, depending on the password strength. Helper texts, which have been added later than others, are supposed to indicate a higher password strength.