code: public VersionConstraint getVersionConstraint(String rawConstraint)
      {
          VersionConstraint constraint = this.versionConstrains.get(rawConstraint);
  
          if (constraint == null) {
              constraint = new DefaultVersionConstraint(rawConstraint);
  
              this.versionConstrains.put(rawConstraint, constraint);
          }
  
          return constraint;
      }
docs: Store and return a weak reference equals to the passed version constraint.
  
  @param rawConstraint the version constraint to find
  @return unique instance of {@link VersionConstraint} equals to the passed one