code: protected ReferenceType referenceType(VirtualMachine vm, String name) {
          return toReferenceType.computeIfAbsent(name, n -> nameToRef(vm, n));
      }
docs: Returns the JDI {@link ReferenceType} corresponding to the specified
  class name.
  
  @param vm the current JDI {@link VirtualMachine} as returned by
  {@code vm()}
  @param name the class name to look-up
  @return the corresponding {@link ReferenceType}