import edu.umd.cs.findbugs.annotations.ExpectWarning;
   import edu.umd.cs.findbugs.annotations.NoWarning;

   abstract class AbstractMissingHashCode {
       int x;

       @Override
       @ExpectWarning("HE_EQUALS_USE_HASHCODE")
       public boolean equals(Object o) {
          if (!(o instanceof AbstractMissingHashCode))
              return false;
          return x == ((AbstractMissingHashCode) o).x;
      }

      @ExpectWarning("HE_INHERITS_EQUALS_USE_HASHCODE")
      static class StillMissingHashCode extends AbstractMissingHashCode {
          int y;
      }

      static class Concrete extends StillMissingHashCode {
          public int z;

          @Override
          @NoWarning("HE")
          public int hashCode(){
              return 0;
          }

          @ExpectWarning("EQ_UNUSUAL")
          @Override
          public boolean equals(Object o) {
              // #303 Request for check <int var> += <double val>
              int sum = 5;
              sum += 4.2; // same as sum = (int)(sum + 4.2);
              System.out.println(sum);
              return o == this;
          }
      }

      @ExpectWarning("EQ_DOESNT_OVERRIDE_EQUALS")
      static class ConcreteMissingEquals extends Concrete {
          int z;
      }
  }