code: public static SchemaCatalog makeCoreSchemaCatalog()
    {
      return SchemaCatalog(
              Sbol2Terms.sbol2.namespacedUri("/schemaexample/core"),
              ImportedSchemas(),
              DocumentSchemas(
                      DocumentSchema(
                              Sbol2Terms.sbol2.namespacedUri("/schema/identified"),
                              Extends(),
                              IdentifierSchemas(),
                              TypeSchemas(),
                              PropertySchemas()
                      ),
                      DocumentSchema(
                              Sbol2Terms.sbol2.namespacedUri("/schema/documented"),
                              Extends(Sbol2Terms.sbol2.namespacedUri("/schema/identified")),
                              IdentifierSchemas(),
                              TypeSchemas(),
                              PropertySchemas(
                                      PropertySchema(
                                              TypeSchemas(
                                                      TypeSchema(Sbol2Terms.documented.displayId)
                                              ),
                                              cardinality.required,
                                              PropertyValueSchemas(propertyType.string)
                                      ),
                                      PropertySchema(
                                              TypeSchemas(
                                                      TypeSchema(Sbol2Terms.documented.name)
                                              ),
                                              cardinality.optional,
                                              PropertyValueSchemas(propertyType.string)
                                      ),
                                      PropertySchema(
                                              TypeSchemas(
                                                      TypeSchema(Sbol2Terms.documented.description)
                                              ),
                                              cardinality.optional,
                                              PropertyValueSchemas(propertyType.string)
                                      )
                              )
                      )
              )
      );
    }
docs: Creates a {@link SchemaCatalog} for the SBOL20 core objects
  @return {@link SchemaCatalog}