yeah.. abc123 has each character - a,b,c,1,2,3 only once.
aabb has each letter twice - a:2 , b:2.
So, each character has to be in multiples of same numbers

The testcase seems incorrect. This statement is correct. But when I found the actual solution then I got to know that there is no issue in test case.

 int set1 = (a+b)*c;  
  int set2 = (a+c)*b; <---  this should be the correct answer as it is max. value among all.
  int set3 = (b+c)*a;
  int set4 = a + b + c; <--- but instead this one is chosen as answer in test case. which is incorrect.
  int set5 = a*b*c;

public class ExpressionsMatter {
@Test
public void checkSmallValues() {
assertEquals(5, Kata.expressionsMatter(1, 3, 1));
}

correct. same in my case.