refactor: fixed Optional related warnings in tests

service/src/test/java/cz/muni/fi/pa165/icehockeymanager/facades/TeamManagerFacadeImplTest.java

@@ -95,7 +95,7 @@ public class TeamManagerFacadeImplTest {
         Team team = buildTeamMock(1L, "Boston Bruins");
         when(teamService.findTeam(1L)).thenReturn(Optional.ofNullable(team));
         Player player = buildPlayerMock(1L, "David Pastrnak", team);
-        when(playerService.findPlayer(1L)).thenReturn(Optional.ofNullable(player));
+        when(playerService.findPlayer(1L)).thenReturn(Optional.of(player));
         teamManagerFacade.firePlayer(1L);
         verify(teamService).removePlayerFromTeam(team, player);
         verify(playerService).removeTeamFromPlayer(player, team);

service/src/test/java/cz/muni/fi/pa165/icehockeymanager/facades/UserFacadeImplTest.java

@@ -76,14 +76,14 @@ class UserFacadeImplTest {
         var player = mock(Player.class);
         when(player.getId()).thenReturn(1L);
         when(player.getName()).thenReturn("Satan");
-        when(playerService.findPlayer(1)).thenReturn(Optional.ofNullable(player));
+        when(playerService.findPlayer(1)).thenReturn(Optional.of(player));
 
         var expected = new PlayerDto();
         expected.setId(1L);
         expected.setName("Satan");
 
         Optional<PlayerDto> result = userFacade.findPlayer(1);
-        Assertions.assertThat(result).isEqualTo(Optional.ofNullable(expected));
+        Assertions.assertThat(result).isEqualTo(Optional.of(expected));
         verify(playerService).findPlayer(1);
     }