code: public void addInstance(IReferenceableInstance instance) throws AtlasException {
  
          ClassType classType = typeSystem.getDataType(ClassType.class, instance.getTypeName());
          ITypedReferenceableInstance newInstance = classType.convert(instance, Multiplicity.REQUIRED);
          findReferencedInstancesToPreLoad(newInstance);
          Id id = instance.getId();
          if(mapper.lookupVertex(id) == null) {
              if(id.isAssigned()) {
                  guidsToLookup.add(id);
              }
              else {
                  addToClassMap(classType, instance);
              }
          }
      }
docs: Adds an instance to be loaded.