small changes

build.gradle

@@ -42,8 +42,8 @@ dependencies {
    api 'org.antlr:antlr4-runtime:4.5.3' // Used in OwrlBaseListener
    api 'com.github.masecla22:java-express:0.2.2'
    implementation 'ch.qos.logback:logback-classic:1.3.6' 
-   testImplementation 'org.junit.jupiter:junit-jupiter-api:5.7.0'
-   //testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.7.0'
+   testImplementation 'org.junit.jupiter:junit-jupiter-api:5.9.3'
+   testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.9.3'
 
 }
 

src/main/java/br/unicamp/cst/attention/CFM.java

@@ -34,8 +34,8 @@
  * (i) the sum of the values​generated by the bottom-up feature maps and 
  * (ii) the sum of the values ​​generated by the top-down feature maps. 
  * 
- * If (i) > (ii), the winner of the attentional cycle is classified as bottom-up. 
- * If (ii) > (i), the winner of the attentional cycle is classified as top-down.
+ * If (i) (@code >} (ii), the winner of the attentional cycle is classified as bottom-up. 
+ * If (ii) (@code >} (i), the winner of the attentional cycle is classified as top-down.
  * 
  * @author leolellisr
  * 

src/main/java/br/unicamp/cst/core/entities/MemoryContainer.java

@@ -683,7 +683,7 @@ public synchronized Long getTimestamp(int index) {
          * @param memoryObserver the observer to be added
          */
 	@Override
-	public void addMemoryObserver(MemoryObserver memoryObserver) {
+	public synchronized void addMemoryObserver(MemoryObserver memoryObserver) {
 		for (Memory memory : memories) {
 			memory.addMemoryObserver(memoryObserver);
 		}
@@ -695,7 +695,7 @@ public void addMemoryObserver(MemoryObserver memoryObserver) {
          * @param memoryObserver the observer to be removed
          */
         @Override
-	public void removeMemoryObserver(MemoryObserver memoryObserver) {
+	public synchronized void removeMemoryObserver(MemoryObserver memoryObserver) {
 		for (Memory memory : memories) {
 			memory.removeMemoryObserver(memoryObserver);
 		}

src/main/java/br/unicamp/cst/core/entities/MemoryObject.java

@@ -12,8 +12,8 @@
 package br.unicamp.cst.core.entities;
 
 import java.io.Serializable;
-import java.util.HashSet;
 import java.util.Set;
+import java.util.concurrent.CopyOnWriteArraySet;
 
 /**
  * A Memory Object is a generic information holder, acting as a sign or an
@@ -270,9 +270,9 @@ public boolean equals(Object obj) {
 	 * Add a memory observer to its list
 	 * @param memoryObserver the MemoryObserve to be added
 	 */
-	public void addMemoryObserver(MemoryObserver memoryObserver) {
+	public synchronized void addMemoryObserver(MemoryObserver memoryObserver) {
 		if (this.memoryObservers == null) {
-			this.memoryObservers = new HashSet<MemoryObserver>(); 
+			this.memoryObservers = new CopyOnWriteArraySet<>(); 
 		}
 		this.memoryObservers.add(memoryObserver);
 	}
@@ -281,7 +281,7 @@ public void addMemoryObserver(MemoryObserver memoryObserver) {
 	 * Remove a memory observer from its list
 	 * @param memoryObserver the MemoryObserve to be removed
 	 */
-	public void removeMemoryObserver(MemoryObserver memoryObserver) {
+	public synchronized void removeMemoryObserver(MemoryObserver memoryObserver) {
 		if (this.memoryObservers != null) {
 		    this.memoryObservers.remove(memoryObserver);
                 }