Remove lower-casing of ID Match attributes

Although the names of attributes in DB may be lowercase, the API
names may safely contain both lower and uppercase letters.

model/model-impl/src/main/java/com/evolveum/midpoint/model/impl/correlator/idmatch/IdMatchServiceImpl.java

@@ -365,7 +365,7 @@ private PersonRequest createPersonRequest(
                 String elementName = fromMidPointAttributeName(property.getElementName());
                 String elementRealValue = getStringValue(property);
 
-                generator.writeFieldName(elementName.toLowerCase());
+                generator.writeFieldName(elementName);
                 generator.writeString(elementRealValue);
             }