Handle XML non-root content

Author: chiranSachintha

bvm/ballerina-runtime/src/main/java/io/ballerina/runtime/internal/TypeConverter.java

@@ -113,7 +113,7 @@ public final class TypeConverter {
     public static final String ERROR_MESSAGE_UNION_START = "{";
     public static final String ERROR_MESSAGE_UNION_END = "}";
     public static final String ERROR_MESSAGE_UNION_SEPARATOR = "or";
-    public static final String XML_START_ELEMENT = "<";
+    public static final String XML_DECLARATION = "<?xml ";
 
     public static Object convertValues(Type targetType, Object inputValue) {
         Type inputType = TypeChecker.getType(inputValue);
@@ -975,10 +975,10 @@ public static BDecimal stringToDecimal(String value) throws NumberFormatExceptio
 
     public static BXml stringToXml(String value) throws BError {
         String xml = value.trim();
-        if (!xml.startsWith(XML_START_ELEMENT)) {
-            return XmlUtils.parse("<root>" + value + "</root>").children();
+        if (xml.startsWith(XML_DECLARATION)) {
+            return XmlUtils.parse(xml);
         }
-        return XmlUtils.parse(xml);
+        return XmlUtils.parse("<root>" + value + "</root>").children();
     }
 
     public static RegExpValue stringToRegExp(String value) throws BError {