System.Xml.Schema.SchemaCollectionPreprocessor.PreprocessIdentityConstraint C# (CSharp) Method

        private void PreprocessIdentityConstraint(XmlSchemaIdentityConstraint constraint) {
            bool valid = true;
            PreprocessAnnotation(constraint); //Set parent of annotation child of key/keyref/unique
            if (constraint.Name != null) {
                ValidateNameAttribute(constraint);
                constraint.SetQualifiedName(new XmlQualifiedName(constraint.Name, this.targetNamespace));
            }
            else {
                SendValidationEvent(Res.Sch_MissRequiredAttribute, "name", constraint);
                valid = false;
            }

            if (this.schema.IdentityConstraints[constraint.QualifiedName] != null) {
                SendValidationEvent(Res.Sch_DupIdentityConstraint, constraint.QualifiedName.ToString(), constraint);
                valid = false;
            }
            else {
                this.schema.IdentityConstraints.Add(constraint.QualifiedName, constraint);
            }

            if (constraint.Selector == null) {
                SendValidationEvent(Res.Sch_IdConstraintNoSelector, constraint);
                valid = false;
            }
            if (constraint.Fields.Count == 0) {
                SendValidationEvent(Res.Sch_IdConstraintNoFields, constraint);
                valid = false;
            }
            if (constraint is XmlSchemaKeyref) {
                XmlSchemaKeyref keyref = (XmlSchemaKeyref)constraint;
                if (keyref.Refer.IsEmpty) {
                    SendValidationEvent(Res.Sch_IdConstraintNoRefer, constraint);
                    valid = false;
                }
                else {
                    ValidateQNameAttribute(keyref, "refer", keyref.Refer);
                }
            }
            if (valid) {
                ValidateIdAttribute(constraint);
                ValidateIdAttribute(constraint.Selector);
                SetParent(constraint.Selector, constraint);
                foreach (XmlSchemaXPath field in constraint.Fields) {
                    SetParent(field, constraint);
                    ValidateIdAttribute(field);
                }
            }
        }