#vulnerable code 
                                @NotNull
    @Override
    public String parseUtf8(@NotNull StopCharTester tester) {
        StringBuilder utfReader = acquireStringBuilder();
        parseUtf8(utfReader, tester);
        return stringInterner().intern(utfReader);
    } 
                            #location 6 
                            #vulnerability type THREAD_SAFETY_VIOLATION
#fixed code
                                @NotNull
    @Override
    public String parseUtf8(@NotNull StopCharTester tester) {
        StringBuilder utfReader = acquireStringBuilder();
        parseUtf8(utfReader, tester);
        return SI.intern(utfReader);
    }