Write an implementation of the following Java method; it is passed a String and an integer length and returns the prefix substring of the given length from the gven String, prefixo (String str, int len) -> String * method return the prefix with lon characters from the string at sethod assumes the string str has at least lon characters * ex: prefixor (Hello, World", 5) -> "Hello ***1 prefixot(abodet" 6) -> "abodet