Refactoring to use CoercionConfigs so as not to need ValueInstantiator

Author: cowtowncoder

src/main/java/com/fasterxml/jackson/dataformat/xml/JacksonXmlModule.java

@@ -2,9 +2,9 @@
 
 import com.fasterxml.jackson.databind.AnnotationIntrospector;
 import com.fasterxml.jackson.databind.module.SimpleModule;
+
 import com.fasterxml.jackson.dataformat.xml.deser.FromXmlParser;
 import com.fasterxml.jackson.dataformat.xml.deser.XmlBeanDeserializerModifier;
-import com.fasterxml.jackson.dataformat.xml.deser.XmlBeanInstantiator;
 import com.fasterxml.jackson.dataformat.xml.deser.XmlStringDeserializer;
 import com.fasterxml.jackson.dataformat.xml.ser.XmlBeanSerializerModifier;
 
@@ -72,9 +72,6 @@ public void setupModule(SetupContext context)
         // as well as AnnotationIntrospector
         context.insertAnnotationIntrospector(_constructIntrospector());
 
-        // 2.11 adds ValueInstantiator, too
-        context.addValueInstantiators(new XmlBeanInstantiator.Provider());
-
         // and finally inform XmlFactory about overrides, if need be:
         if (_cfgNameForTextElement != FromXmlParser.DEFAULT_UNNAMED_TEXT_PROPERTY) {
             XmlMapper m = (XmlMapper) context.getOwner();

src/main/java/com/fasterxml/jackson/dataformat/xml/XmlMapper.java

@@ -10,6 +10,8 @@
 import com.fasterxml.jackson.core.*;
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.*;
+import com.fasterxml.jackson.databind.cfg.CoercionAction;
+import com.fasterxml.jackson.databind.cfg.CoercionInputShape;
 import com.fasterxml.jackson.databind.cfg.MapperBuilder;
 import com.fasterxml.jackson.databind.jsontype.PolymorphicTypeValidator;
 import com.fasterxml.jackson.databind.jsontype.TypeResolverBuilder;
@@ -146,9 +148,8 @@ public XmlMapper(JacksonXmlModule module) {
 
     public XmlMapper(XmlFactory xmlFactory, JacksonXmlModule module)
     {
-        /* Need to override serializer provider (due to root name handling);
-         * deserializer provider fine as is
-         */
+        // Need to override serializer provider (due to root name handling);
+        // deserializer provider fine as is
         super(xmlFactory, new XmlSerializerProvider(new XmlRootNameLookup()), null);
         _xmlModule = module;
         // but all the rest is done via Module interface!
@@ -165,6 +166,15 @@ public XmlMapper(XmlFactory xmlFactory, JacksonXmlModule module)
         //    Base64 default as "MIME" (not MIME-NO-LINEFEEDS), to preserve pre-2.12
         //    behavior
         setBase64Variant(Base64Variants.MIME);
+
+        // 04-Jun-2020, tatu: Use new (2.12) "CoercionConfigs" to support coercion
+        //   from empty and blank Strings to "empty" POJOs etc
+        coercionConfigDefaults()
+            // To allow indentation without problems, need to accept blank String as empty:
+            .setAcceptBlankAsEmpty(Boolean.TRUE)
+            // and then coercion from empty String to empty value, in general
+            .setCoercion(CoercionInputShape.EmptyString, CoercionAction.AsEmpty)
+        ;
     }
 
     /**

src/main/java/com/fasterxml/jackson/dataformat/xml/deser/XmlBeanDeserializerModifier.java

@@ -100,7 +100,7 @@ public JsonDeserializer<?> modifyDeserializer(DeserializationConfig config,
         //    coercion.
         // 30-Apr-2020, tatu: Complication from [dataformat-xml#318] as we now
         //    have a delegate too...
-        if ((inst instanceof XmlBeanInstantiator) || !inst.canCreateFromString()) {
+        if (!inst.canCreateFromString()) {
             SettableBeanProperty textProp = _findSoleTextProp(config, deser.properties());
             if (textProp != null) {
                 return new XmlTextDeserializer(deser, textProp);

src/main/java/com/fasterxml/jackson/dataformat/xml/deser/XmlBeanInstantiator.java

@@ -4,6 +4,7 @@
 import java.util.List;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
+
 import com.fasterxml.jackson.dataformat.xml.*;
 
 // for [dataformat-xml#124]