Make ToXml and ToJson work via the new POCO serializers

[ewoutkramer]

ToXml(Base) and ToJson(Base) still work via PocoElementNode, but should work via the more native route. This is in principle independent of the new direct implementation of ITypedElement, but in line with making the new serializers work on IScopedNode. It also takes these two extension methods logicalky out of the domain of typedelement, and into the poco domain.

[ewoutkramer]

Actually, we should go after all "transformations" and see which ones should be done via POCO's now.

[ewoutkramer]

This means we need to remove the JsonBuilder and XmlBuilder and make up our mind what to support from the legacy SerializerSettings classes. Too much for alpha1, will need to postpone.

[ewoutkramer]

Big refactoring, relatively small number of breaking changes. Mostly around unifying (or actually: abolishing) the serializer settings, as most of the settings did not make sense anyway. See the wiki for details about that change: https://github.com/FirelyTeam/firely-net-sdk/wiki/Breaking-changes-in-6.0#breaking-changes-to-the-serializers.

Other than that, I have cleaned up the serializers, rejuvenating the old serializers to use the new serializers. So we cannot make a distinction anymore ;-) This is what the serializer hierarchy looks like now:

classDiagram
    BaseFhirXmlSerializer <|-- FhirXmlSerializer
    BaseFhirXmlSerializer <|-- BaseFhirXmlPocoSerializer
    BaseFhirXmlPocoSerializer <|-- FhirXmlPocoSerializer

    class BaseFhirXmlSerializer{
    }
    class FhirXmlSerializer{
    }
    class BaseFhirXmlPocoSerializer{
       << Obsolete >>
    }
    class FhirXmlPocoSerializer{
       << Obsolete >>
    }

Loading

I have kept the obsolete classes around to get compile-compatibility, but they are simply empty subclasses and just there as a syntactical trick. The obsolete attributes will help people migrate.

ToXml/ToJson/WriteTo will now:

• Use the new serializers when called on Base.
• Use the new serializers when called on ITypedElement, when the ITypedElement is really a POCO
• Use the legacy serializers when called on a "real" ITypedElement.

Note that poco.ToTypedElement() will result in an ITypedElement that will fall under bullet 2 above. You'd have to do poco.ToTypedElementLegacy() to become a "real" ITypedElement.

[ewoutkramer]

Just for documentation, this was the old situation:

ToSourceNode(ITypedElement) - Base / Hl7.Fhir.ElementModel.ElementNodeExtensions
ToSourceNode(Base,ModelInspector) - Base / Hl7.Fhir.ElementModel.PocoBuilderExtensions

ToTypedElement(ISourceNode, ISDSP) - Base / Hl7.Fhir.ElementModel.SourceNodeExtensions
ToTypedElement(ISourceNode) - Base / Hl7.Fhir.ElementModel.SourceNodeExtensions
ToTypedElementLegacy(Base, ModelInspector) - Base / Hl7.Fhir.ElementModel.TypedElementExtensions
ToTypedElement(Base, ModelInspector) - Base / Hl7.Fhir.ElementModel.TypedElementExtensions
ToTypedElementLegacy(Base) - Shims STU3+ / Hl7.Fhir.ElementModel.ShimsTypedElementExtensions
ToTypedElement(Base) - Shims STU3+ / Hl7.Fhir.ElementModel.ShimsTypedElementExtensions

ToElementNode(Base) - Base / Hl7.Fhir.ElementModel.TypedElementExtensions

ToXml(ISourceNode, FXSSettings) - Base / Hl7.Fhir.Serialization.FhirXmlBuilderExtensions
WriteTo(ISourceNode, XmlWriter, FXSSettings)- Base / Hl7.Fhir.Serialization.FhirXmlBuilderExtensions
ToXml(ITypedElement, FXSSettings) - Base / Hl7.Fhir.Serialization.FhirXmlBuilderExtensions
WriteTo(ITypedElement, XmlWriter, FXSSettings)- Base / Hl7.Fhir.Serialization.FhirXmlBuilderExtensions
ToXml(Base, FXSSettings) - Shims STU3+ / Hl7.Fhir.Serialization.PocoSerializationExtensions


ToJson(ISourceNode, FJSSettings) - Base / Hl7.Fhir.Serialization.FhirJsonBuilderExtensions
WriteTo(ISourceNode, JsonWriter, FJSSettings)- Base / Hl7.Fhir.Serialization.FhirJsonBuilderExtensions
ToJson(ITypedElement, FJSSettings) - Base / Hl7.Fhir.Serialization.FhirJsonBuilderExtensions
WriteTo(ITypedElement, JsonWriter, FJSSettings)- Base / Hl7.Fhir.Serialization.FhirJsonBuilderExtensions
ToJson(Base, FJSSettings) - Shims STU3+ / Hl7.Fhir.Serialization.PocoSerializationExtensions


* Note: the FhirJsonSerializationSettings and FhirXmlSerializationSettings are used by the FhirJsonBuilder and FhirXmlBuilder respectively.

(old) BaseFhirSerializer
(old) CommonFhirXmlSerializer
	SerializeToString(Base,summary,root)
	SerializeToStringAsync(Base, summarytype, root, elements)
	SerializeToBytes(Base,root) + async
	SerializeToBytesAsync(Base, summarytype, root, elements)
	SerializeToDocument(Base, summarytype, root, elements)
	Serialize(Base, XmlWriter, SummaryType,root, elements)
	SerializeAsync(Base, XmlWriter, SummaryType,root, elements)

(old) CommonFhirJsonSerializer
	SerializeToString(Base,summary) + async
	SerializeToBytes(Base) + async
	SerializeToDocument(Base): JObject
	Serialize(Base, JsonWriter, SummaryType, elements)
	SerializeAsync(Base, JsonWriter, SummaryType, elements)


(old) FhirXmlSerializer (+SerializerSettings)
(old) FhirJsonSerializer (+SerializerSettings)


BaseFhirXmlPocoSerializer
	Serialize(Base,XmlWriter,SerializationFilter)
	ext SerializeToString(Base,SerializationFilter)

BaseFhirJsonPocoSerializer
	Serialize(Base,Utf8JsonWriter writer)
	ext SerializeToString(Base)

FhirXmlPocoSerializer (no settings?)
FhirJsonPocoSerializer (+FhirJsonPocoSerializerSettings)


SerializerSettings
   public bool Pretty { get; set; } // = false;
   public bool TrimWhiteSpacesInXml { get; set; } = true;
   public bool IncludeMandatoryInElementsSummary { get; set; } = false;

FhirJsonPocoSerializerSettings
   public SerializationFilter? SummaryFilter { get; set; } = default;

FhirXmlSerializationSettings
   public bool IgnoreUnknownElements;
   public bool Pretty { get; set; } // = false;
   public bool TrimWhitespaces { get; set; } = true;

FhirJsonSerializationSettings
   public bool IgnoreUnknownElements;
   public bool Pretty { get; set; } // = false;