code: public synchronized K reverseLookup(final V value) {
          if (tmap == null) {
              throw new IllegalStateException("not open");
          }
          return invTmap.findKeyForValue(value);
      }
docs: Performs a reverse lookup for the given {@code value}.
  If multiple keys resolve to the same value, this method
  will return the first key match as per the JDBM impl.
  
  @param value
  @return
  @see InverseHashView#findKeyForValue(Object)