refactor(distributed-lock): Minor refactoring to avoid deprecated calls

Author: alturkovic

distributed-lock-core/src/main/java/com/github/alturkovic/lock/AbstractSimpleLock.java

@@ -46,19 +46,19 @@ public String acquire(final List<String> keys, final String storeId, final long
       throw new IllegalStateException("Cannot lock with empty token");
     }
 
-    return acquire(keys.get(0), storeId, token, expiration);
+    return acquire(keys.getFirst(), storeId, token, expiration);
   }
 
   @Override
   public boolean release(final List<String> keys, final String storeId, final String token) {
     Assert.isTrue(keys.size() == 1, "Cannot release lock for multiple keys with this lock");
-    return release(keys.get(0), storeId, token);
+    return release(keys.getFirst(), storeId, token);
   }
 
   @Override
   public boolean refresh(final List<String> keys, final String storeId, final String token, final long expiration) {
     Assert.isTrue(keys.size() == 1, "Cannot refresh lock for multiple keys with this lock");
-    return refresh(keys.get(0), storeId, token, expiration);
+    return refresh(keys.getFirst(), storeId, token, expiration);
   }
 
   protected abstract String acquire(String key, String storeId, String token, long expiration);

distributed-lock-core/src/main/java/com/github/alturkovic/lock/key/SpelKeyGenerator.java

@@ -60,7 +60,7 @@ public List<String> resolveKeys(final String lockKeyPrefix, final String express
       throw new EvaluationConvertException("null keys are not supported: " + keys);
     }
 
-    if (StringUtils.isEmpty(lockKeyPrefix)) {
+    if (!StringUtils.hasText(lockKeyPrefix)) {
       return keys;
     }
 

distributed-lock-core/src/main/java/com/github/alturkovic/lock/retry/RetriableLock.java

@@ -46,7 +46,7 @@ public String acquire(final List<String> keys, final String storeId, final long
       return retryTemplate.execute(ctx -> {
         final String token = lock.acquire(keys, storeId, expiration);
 
-        if (StringUtils.isEmpty(token)) {
+        if (!StringUtils.hasText(token)) {
           throw new LockNotAvailableException(String.format("Lock not available for keys: %s in store %s", keys, storeId));
         }