System.Xml.Schema.SchemaCollectionCompiler.CannonicalizeGroupRef C# (CSharp) Méthode

        private XmlSchemaParticle CannonicalizeGroupRef(XmlSchemaGroupRef groupRef, bool root,  bool substitution) {
            XmlSchemaGroup group;
            if (groupRef.Redefined != null) {
                group = groupRef.Redefined;
            }
            else {
                group = (XmlSchemaGroup)this.schema.Groups[groupRef.RefName];
            }
            if (group == null) {
                SendValidationEvent(Res.Sch_UndefGroupRef, groupRef.RefName.ToString(), groupRef);
                return XmlSchemaParticle.Empty;
            }
            if (group.CanonicalParticle == null) {
                CompileGroup(group);
            }
            if (group.CanonicalParticle == XmlSchemaParticle.Empty) {
                return XmlSchemaParticle.Empty;
            }
            XmlSchemaGroupBase groupBase = (XmlSchemaGroupBase)group.CanonicalParticle;
            if (groupBase is XmlSchemaAll) {
                if (!root) {
                    SendValidationEvent(Res.Sch_AllRefNotRoot, "", groupRef);
                    return XmlSchemaParticle.Empty;
                }
                if (groupRef.MinOccurs != decimal.One || groupRef.MaxOccurs != decimal.One) {
                    SendValidationEvent(Res.Sch_AllRefMinMax, groupRef);
                    return XmlSchemaParticle.Empty;
                }
            }
            else if (groupBase is XmlSchemaChoice && groupBase.Items.Count == 0) {
                if (groupRef.MinOccurs != decimal.Zero) {
                    SendValidationEvent(Res.Sch_EmptyChoice, groupRef, XmlSeverityType.Warning);
                }
                return XmlSchemaParticle.Empty;
            }
            XmlSchemaGroupBase groupRefBase = (
                (groupBase is XmlSchemaSequence) ? (XmlSchemaGroupBase)new XmlSchemaSequence() :
                (groupBase is XmlSchemaChoice)   ? (XmlSchemaGroupBase)new XmlSchemaChoice() :
                                                   (XmlSchemaGroupBase)new XmlSchemaAll()
            );
            groupRefBase.MinOccurs = groupRef.MinOccurs;
            groupRefBase.MaxOccurs = groupRef.MaxOccurs;
            foreach (XmlSchemaParticle particle in groupBase.Items) {
                groupRefBase.Items.Add(particle);
            }
            groupRef.SetParticle(groupRefBase);
            return groupRefBase;
        }