Logging does not work if written in lowercase(hazelcast.logging.level) [API-1740]

src/util/Util.ts

@@ -69,7 +69,7 @@ export function shuffleArray<T>(array: T[]): void {
 
 /** @internal */
 export function enumFromString<T>(enumType: any, value: string): T {
-    return enumType[value.toUpperCase()];
+    return enumType[value ? value.toUpperCase() : value];
 }
 
 /** @internal */