question: @ Nullable public String loadString ( @ Nullable String messagesPack , @ Nullable String ref ) { if ( ref != null ) { if ( ref . startsWith ( MARK ) ) { String path = ref . substring ( 6 ) ; final String [ ] strings = path . split ( "/" ) ; if ( strings . length == 1 && messagesPack != null ) { ref = messages . getMessage ( messagesPack , strings [ 0 ] ) ; } else if ( strings . length == 2 ) { ref = messages . getMessage ( strings [ 0 ] , strings [ 1 ] ) ; } else { throw new UnsupportedOperationException ( "Unsupported resource string format: '" + ref + "', messagesPack=" + messagesPack ) ; } } else if ( ref . startsWith ( MAIN_MARK ) ) { String path = ref . substring ( 10 ) ; return messages . getMainMessage ( path ) ; } } return ref ; }
target:  Get localized message by reference provided in full or brief format.