code: public OSchemaHelper linkedType(OType linkedType)
  	{
  		checkOProperty();
  		if(!Objects.equal(linkedType, lastProperty.getLinkedType()))
  		{
  			lastProperty.setLinkedType(linkedType);
  		}
  		return this;
  	}
docs: Set linked type to a current property
  @param linkedType {@link OType} to set as a linked type
  @return this helper