Make observation immutable and implement equals/hashcode

leshan-core/src/main/java/org/eclipse/leshan/core/observation/Observation.java

@@ -15,6 +15,9 @@
  *******************************************************************************/
 package org.eclipse.leshan.core.observation;
 
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
 import java.util.Map;
 
 import org.eclipse.leshan.core.node.LwM2mPath;
@@ -25,10 +28,10 @@
  */
 public class Observation {
 
-    private byte[] id;
-    private LwM2mPath path;
-    private String registrationId;
-    private Map<String, String> context;
+    private final byte[] id;
+    private final LwM2mPath path;
+    private final String registrationId;
+    private final Map<String, String> context;
 
     /**
      * Instantiates an {@link Observation} for the given node path.
@@ -42,7 +45,10 @@ public Observation(byte[] id, String registrationId, LwM2mPath path, Map<String,
         this.id = id;
         this.path = path;
         this.registrationId = registrationId;
-        this.context = context;
+        if (context != null)
+            this.context = Collections.unmodifiableMap(new HashMap<>(context));
+        else
+            this.context = Collections.emptyMap();
     }
 
     /**
@@ -83,4 +89,45 @@ public String toString() {
         return String.format("Observation [id=%s, path=%s, registrationId=%s, context=%s]", Hex.encodeHexString(id),
                 path, registrationId, context);
     }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((context == null) ? 0 : context.hashCode());
+        result = prime * result + Arrays.hashCode(id);
+        result = prime * result + ((path == null) ? 0 : path.hashCode());
+        result = prime * result + ((registrationId == null) ? 0 : registrationId.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        Observation other = (Observation) obj;
+        if (context == null) {
+            if (other.context != null)
+                return false;
+        } else if (!context.equals(other.context))
+            return false;
+        if (!Arrays.equals(id, other.id))
+            return false;
+        if (path == null) {
+            if (other.path != null)
+                return false;
+        } else if (!path.equals(other.path))
+            return false;
+        if (registrationId == null) {
+            if (other.registrationId != null)
+                return false;
+        } else if (!registrationId.equals(other.registrationId))
+            return false;
+        return true;
+    }
+
 }