code: public boolean containsValue(Object value) {
          Entry tab[] = mTable;
          
          if (value == null) {
              for (int i = tab.length ; i-- > 0 ;) {
                  for (Entry e = tab[i], prev = null; e != null; e = e.mNext) {
                      if (e.getKey() == null) {
                          // Clean up after a cleared Reference.
                          mModCount++;
                          if (prev != null) {
                              prev.mNext = e.mNext;
                          }
                          else {
                              tab[i] = e.mNext;
                          }
                          mCount--;
                      }
                      else if (e.mValue == null) {
                          return true;
                      }
                      else {
                          prev = e;
                      }
                  }
              }
          }
          else {
              for (int i = tab.length ; i-- > 0 ;) {
                  for (Entry e = tab[i], prev = null; e != null; e = e.mNext) {
                      if (e.getKey() == null) {
                          // Clean up after a cleared Reference.
                          mModCount++;
                          if (prev != null) {
                              prev.mNext = e.mNext;
                          }
                          else {
                              tab[i] = e.mNext;
                          }
                          mCount--;
                      }
                      else if (value.equals(e.mValue)) {
                          return true;
                      }
                      else {
                          prev = e;
                      }
                  }
              }
          }
  
          return false;
      }
docs: Returns <tt>true</tt> if this map maps one or more keys to the
  specified value.
  
  @param value value whose presence in this map is to be tested.
  @return <tt>true</tt> if this map maps one or more keys to the
  specified value.