public override BidiMap inverseBidiMap()
 {
     if (inverse == null)
     {
         inverse         = new UnmodifiableBidiMap(getBidiMap().inverseBidiMap());
         inverse.inverse = this;
     }
     return(inverse);
 }
 public override BidiMap inverseBidiMap()
 {
     if (inverse == null)
     {
         inverse = new UnmodifiableBidiMap(getBidiMap().inverseBidiMap());
         inverse.inverse = this;
     }
     return inverse;
 }