ADDITIONAL SYSTEM INFORMATION :
All OS/JRE

A DESCRIPTION OF THE PROBLEM :
A test might describe the problem the best:

@Test
public void hashMapTest()
{
   Map<UUID, UUID> map = new HashMap<>();
   for (int i = 0; i < 10; i++)
   {
      UUID uuid = UUID.randomUUID();
      map.computeIfAbsent(uuid, key ->
      {
         map.put(uuid,uuid);
         return uuid;
      });
   }
   assertThat(map.size(), is(10));
}


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
@Test
public void hashMapTest()
{
   Map<UUID, UUID> map = new HashMap<>();
   for (int i = 0; i < 10; i++)
   {
      UUID uuid = UUID.randomUUID();
      map.computeIfAbsent(uuid, key ->
      {
         map.put(uuid,uuid);
         return uuid;
      });
   }
   assertThat(map.size(), is(10));
}


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
green test
ACTUAL -
red test, double enntries

---------- BEGIN SOURCE ----------
@Test
public void hashMapTest()
{
   Map<UUID, UUID> map = new HashMap<>();
   for (int i = 0; i < 10; i++)
   {
      UUID uuid = UUID.randomUUID();
      map.computeIfAbsent(uuid, key ->
      {
         map.put(uuid,uuid);
         return uuid;
      });
   }
   assertThat(map.size(), is(10));
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
fix the code and do not add the value inside the computeIfAbsent method