fixed some findbugs warnings

CHANGELOG.md

 Upcoming version:
 -----------------
+  - fixed some findbugs warnings (Nikolaus Krismer)
   - implemented various different types for node queue (Nikolaus Krismer)
   - externalizing dependency versions (Nikolaus Krismer)
   - added configuration for vienna (Nikolaus Krismer)

src/main/java/it/unibz/inf/isochrone/algorithm/queue/NodeQueueBinaryHeap.java

@@ -15,7 +15,7 @@ class NodeQueueBinaryHeap<T extends INode> implements INodeQueue<T> {
 
 	// Constructor
 
-	public NodeQueueBinaryHeap() {
+	NodeQueueBinaryHeap() {
 		this.nodeQueue = BinaryHeapFactory.getInstance().create((n1, n2) -> n1.compareTo(n2));
 		this.nodeQueueEntries = new HashMap<>();
 	}

src/main/java/it/unibz/inf/isochrone/algorithm/queue/NodeQueueFactory.java

@@ -6,7 +6,7 @@ public final class NodeQueueFactory {
 
 	private NodeQueueFactory() { }
 
-	public final static <T extends INode> INodeQueue<T> getInstance(final QueueType type) {
+	public static <T extends INode> INodeQueue<T> getInstance(final QueueType type) {
 		if (type == QueueType.BINARY_HEAP) {
 			return new NodeQueueBinaryHeap<>();
 		}

src/main/java/it/unibz/inf/isochrone/algorithm/queue/NodeQueueFibonacciHeap.java

@@ -11,7 +11,7 @@ class NodeQueueFibonacciHeap<T extends INode> implements INodeQueue<T> {
 
 	// Constructor
 
-	public NodeQueueFibonacciHeap() {
+	NodeQueueFibonacciHeap() {
 		// FibonacciHeap serves as a PriorityQueue (without the need to remove entries before adding them)
 		// To find HeapEntries we use a HashMap...
 		// ...although we need two structures this is still way faster than using a PriorityQueue alone

src/main/java/it/unibz/inf/isochrone/algorithm/queue/NodeQueuePriorityQueue.java

@@ -9,7 +9,7 @@ class NodeQueuePriorityQueue<T extends INode> implements INodeQueue<T> {
 
 	// Constructor
 
-	public NodeQueuePriorityQueue() {
+	NodeQueuePriorityQueue() {
 		this.nodeQueue = new PriorityQueue<>();
 	}