Refactor Infinispan example (#3684)

* Refactor Infinispan examples

* Refactor Infinispan examples

libraries/src/main/java/com/baeldung/infinispan/CacheConfiguration.java

@@ -20,8 +20,7 @@ public class CacheConfiguration {
     public static final String TRANSACTIONAL_CACHE = "transactional-cache";
 
     public DefaultCacheManager cacheManager() {
-        DefaultCacheManager cacheManager = new DefaultCacheManager();
-        return cacheManager;
+        return new DefaultCacheManager();
     }
 
     public Cache<String, Integer> transactionalCache(DefaultCacheManager cacheManager, CacheListener listener) {

libraries/src/main/java/com/baeldung/infinispan/listener/CacheListener.java

@@ -40,9 +40,7 @@ public class CacheListener {
     @CacheEntriesEvicted
     public void entriesEvicted(CacheEntriesEvictedEvent<String, String> event) {
         final StringBuilder builder = new StringBuilder();
-        event.getEntries().entrySet().forEach((e) ->
-                builder.append(e.getKey() + ", ")
-        );
+        event.getEntries().forEach((key, value) -> builder.append(key).append(", "));
         System.out.println("Evicting following entries from cache: " + builder.toString());
     }
 

libraries/src/main/java/com/baeldung/infinispan/service/HelloWorldService.java

@@ -31,12 +31,7 @@ public class HelloWorldService {
 
     public String findSimpleHelloWorld() {
         String cacheKey = "simple-hello";
-        String helloWorld = simpleHelloWorldCache.get(cacheKey);
-        if (helloWorld == null) {
-            helloWorld = repository.getHelloWorld();
-            simpleHelloWorldCache.put(cacheKey, helloWorld);
-        }
-        return helloWorld;
+        return simpleHelloWorldCache.computeIfAbsent(cacheKey, k -> repository.getHelloWorld());
     }
 
     public String findExpiringHelloWorld() {
@@ -79,12 +74,7 @@ public class HelloWorldService {
     }
 
     public String findPassivatingHelloWorld(String key) {
-        String value = passivatingHelloWorldCache.get(key);
-        if(value == null) {
-            value = repository.getHelloWorld();
-            passivatingHelloWorldCache.put(key, value);
-        }
-        return value;
+        return passivatingHelloWorldCache.computeIfAbsent(key, k -> repository.getHelloWorld());
     }
 
 }