Very slow solution

I like this OOP guy

This solution may seems heavy, but it works extremely fast due to use recursion and primitive chars

Some benchmark tests with given input string:

private static final String TEST_STRING = "cat mat d3y b5n s2s sat a is on the m8c".repeat(10);

Benchmark                         Mode  Cnt   Score   Error  Units
MainTest.abbreviateWithRecursion    ss   10   1,944 ± 0,291  ms/op
MainTest.abbreviateWithRegexp       ss   10  14,045 ± 1,272  ms/op

private static final String TEST_STRING = "cat mat d3y b5n s2s sat a is on the m8c".repeat(100);

Benchmark                         Mode  Cnt   Score   Error  Units
MainTest.abbreviateWithRecursion    ss   10   7,164 ± 2,597  ms/op
MainTest.abbreviateWithRegexp       ss   10  31,115 ± 7,544  ms/op

is O(n^2) here ?

Nice to read

God of Java was here..