These methods send #isHealthy, but it is not implemented in Squeak: * Dictionary>>#stonPostReferenceResolution * Set>>#stonPostReferenceResolution * STONReaderTest>>#testDictionaryWithIndirectReferenceKeys * STONReaderTest>>#testDictionaryWithReferenceKeys * STONReaderTest>>#testSetWithIndirectReferenceElements * STONReaderTest>>#testSetWithReferenceElements