Improved class model generation

All PMMLObject subclasses are expected to have type-level
@XmlRootElement and @JsonRootName annotations.

pmml-model/src/test/java/org/jpmml/model/visitors/VersionDowngraderTest.java

@@ -18,6 +18,7 @@
 import org.dmg.pmml.time_series.TrendExpoSmooth;
 import org.jpmml.model.ReflectionUtil;
 import org.jpmml.model.UnsupportedAttributeException;
+import org.jpmml.model.UnsupportedElementException;
 import org.junit.Test;
 
 import static org.junit.Assert.assertEquals;
@@ -159,7 +160,7 @@ public void downgradeTrendExpoSmooth(){
 
 		try {
 			downgrade(trendExpoSmooth, Version.PMML_4_0);
-		} catch(IllegalArgumentException iae){
+		} catch(UnsupportedElementException uee){
 			// Ignored
 		}
 	}

pmml-xjc/src/main/java/org/jpmml/xjc/CodeModelUtil.java

@@ -3,9 +3,18 @@
  */
 package org.jpmml.xjc;
 
+import java.io.IOException;
+import java.io.StringWriter;
+import java.lang.reflect.AccessibleObject;
+import java.lang.reflect.Field;
+import java.util.Collection;
 import java.util.List;
 
+import com.sun.codemodel.JAnnotatable;
+import com.sun.codemodel.JAnnotationUse;
 import com.sun.codemodel.JClass;
+import com.sun.codemodel.JFormatter;
+import com.sun.codemodel.JGenerable;
 import com.sun.codemodel.JType;
 
 public class CodeModelUtil {
@@ -24,4 +33,89 @@ public JType getElementType(JType collectionType){
 
 		return elementTypes.get(0);
 	}
+
+	static
+	public boolean hasAnnotation(Collection<JAnnotationUse> annotations, Class<?> clazz){
+		JAnnotationUse annotation = findAnnotation(annotations, clazz);
+
+		return (annotation != null);
+	}
+
+	static
+	public JAnnotationUse findAnnotation(Collection<JAnnotationUse> annotations, Class<?> clazz){
+		String fullName = clazz.getName();
+
+		for(JAnnotationUse annotation : annotations){
+			JClass type = annotation.getAnnotationClass();
+
+			if((type.fullName()).equals(fullName)){
+				return annotation;
+			}
+		}
+
+		return null;
+	}
+
+	static
+	public List<JAnnotationUse> getAnnotations(JAnnotatable annotatable){
+
+		try {
+			Class<?> clazz = annotatable.getClass();
+
+			Field annotationsField;
+
+			while(true){
+
+				try {
+					annotationsField = clazz.getDeclaredField("annotations");
+
+					break;
+				} catch(NoSuchFieldException nsfe){
+					clazz = clazz.getSuperclass();
+
+					if(clazz == null){
+						throw nsfe;
+					}
+				}
+			}
+
+			ensureAccessible(annotationsField);
+
+			return (List)annotationsField.get(annotatable);
+		} catch(ReflectiveOperationException roe){
+			throw new RuntimeException(roe);
+		}
+	}
+
+	static
+	public String stringValue(JGenerable generable){
+		String result;
+
+		try(StringWriter writer = new StringWriter()){
+			generable.generate(new JFormatter(writer));
+
+			result = writer.toString();
+		} catch(IOException ioe){
+			throw new RuntimeException(ioe);
+		}
+
+		if(result.length() >= 2 && (result.startsWith("\"") && result.endsWith("\""))){
+			result = result.substring(1, result.length() - 1);
+		} else
+
+		{
+			throw new RuntimeException();
+		}
+
+		return result;
+	}
+
+	@SuppressWarnings("deprecation")
+	static
+	void ensureAccessible(AccessibleObject accessibleObject){
+
+		if(!accessibleObject.isAccessible()){
+			accessibleObject.setAccessible(true);
+		}
+	}
 }

pmml-xjc/src/main/java/org/jpmml/xjc/JacksonPlugin.java

@@ -17,6 +17,7 @@
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
 import com.sun.codemodel.JAnnotationArrayMember;
 import com.sun.codemodel.JAnnotationUse;
+import com.sun.codemodel.JAnnotationValue;
 import com.sun.codemodel.JClass;
 import com.sun.codemodel.JCodeModel;
 import com.sun.codemodel.JDefinedClass;
@@ -38,6 +39,7 @@
 import com.sun.tools.xjc.outline.EnumOutline;
 import com.sun.tools.xjc.outline.FieldOutline;
 import com.sun.tools.xjc.outline.Outline;
+import jakarta.xml.bind.annotation.XmlRootElement;
 import org.xml.sax.ErrorHandler;
 
 public class JacksonPlugin extends Plugin {
@@ -58,14 +60,18 @@ public boolean run(Outline outline, Options options, ErrorHandler errorHandler){
 
 		Collection<? extends ClassOutline> classOutlines = outline.getClasses();
 		for(ClassOutline classOutline : classOutlines){
-			CClassInfo classInfo = classOutline.target;
 			JDefinedClass beanClazz = classOutline.implClass;
 
-			if(classInfo.isElement()){
-				QName elementName = classInfo.getElementName();
+			List<JAnnotationUse> beanClazzAnnotations = CodeModelUtil.getAnnotations(beanClazz);
+
+			JAnnotationUse xmlRootElement = CodeModelUtil.findAnnotation(beanClazzAnnotations, XmlRootElement.class);
+			if(xmlRootElement != null){
+				Map<String, JAnnotationValue> annotationMembers = xmlRootElement.getAnnotationMembers();
+
+				JAnnotationValue nameValue = annotationMembers.get("name");
 
 				JAnnotationUse jsonRootName = beanClazz.annotate(JsonRootName.class)
-					.param("value", elementName.getLocalPart());
+					.param("value", CodeModelUtil.stringValue(nameValue));
 			}
 
 			FieldOutline[] fieldOutlines = classOutline.getDeclaredFields();