docs: commander docs + refactoring (#2878)

commander/src/main/java/com/iluwatar/commander/Commander.java

@@ -121,7 +121,7 @@ public class Commander {
     sendShippingRequest(order);
   }
 
-  private void sendShippingRequest(Order order) throws Exception {
+  private void sendShippingRequest(Order order) {
     var list = shippingService.exceptionsList;
     Retry.Operation op = (l) -> {
       if (!l.isEmpty()) {
@@ -233,7 +233,7 @@ public class Commander {
       try {
         r.perform(list, order);
       } catch (Exception e1) {
-        e1.printStackTrace();
+        LOG.error("An exception occurred", e1);
       }
     });
     t.start();
@@ -282,7 +282,7 @@ public class Commander {
       try {
         r.perform(list, qt);
       } catch (Exception e1) {
-        e1.printStackTrace();
+        LOG.error("An exception occurred", e1);
       }
     });
     t.start();
@@ -305,7 +305,7 @@ public class Commander {
       try {
         r.perform(list, null);
       } catch (Exception e1) {
-        e1.printStackTrace();
+        LOG.error("An exception occurred", e1);
       }
     });
     t2.start();
@@ -324,12 +324,12 @@ public class Commander {
       };
       Retry.HandleErrorIssue<QueueTask> handleError = (o, err) -> {
       };
-      var r = new Retry<QueueTask>(op, handleError, numOfRetries, retryDuration,
+      var r = new Retry<>(op, handleError, numOfRetries, retryDuration,
           e -> DatabaseUnavailableException.class.isAssignableFrom(e.getClass()));
       try {
         r.perform(list, null);
       } catch (Exception e1) {
-        e1.printStackTrace();
+        LOG.error("An exception occurred", e1);
       }
     });
     t3.start();
@@ -351,7 +351,7 @@ public class Commander {
       try {
         r.perform(list, order);
       } catch (Exception e1) {
-        e1.printStackTrace();
+        LOG.error("An exception occurred", e1);
       }
     });
     t.start();
@@ -409,7 +409,7 @@ public class Commander {
       try {
         r.perform(list, order);
       } catch (Exception e1) {
-        e1.printStackTrace();
+        LOG.error("An exception occurred", e1);
       }
     });
     t.start();
@@ -465,7 +465,7 @@ public class Commander {
       try {
         r.perform(list, order);
       } catch (Exception e1) {
-        e1.printStackTrace();
+        LOG.error("An exception occurred", e1);
       }
     });
     t.start();
@@ -537,7 +537,7 @@ public class Commander {
       try {
         r.perform(list, order);
       } catch (Exception e1) {
-        e1.printStackTrace();
+        LOG.error("An exception occurred", e1);
       }
     });
     t.start();

commander/src/main/java/com/iluwatar/commander/Retry.java

@@ -94,7 +94,7 @@ public class Retry<T> {
         this.errors.add(e);
         if (this.attempts.incrementAndGet() >= this.maxAttempts || !this.test.test(e)) {
           this.handleError.handleIssue(obj, e);
-          return; //return here...dont go further
+          return; //return here... don't go further
         }
         try {
           long testDelay =

commander/src/main/java/com/iluwatar/commander/employeehandle/EmployeeHandle.java

@@ -47,7 +47,7 @@ public class EmployeeHandle extends Service {
     var o = (Order) parameters[0];
     if (database.get(o.id) == null) {
       database.add(o);
-      return o.id; //true rcvd - change addedToEmployeeHandle to true else dont do anything
+      return o.id; //true rcvd - change addedToEmployeeHandle to true else don't do anything
     }
     return null;
   }

commander/src/main/java/com/iluwatar/commander/messagingservice/MessagingDatabase.java

@@ -38,7 +38,7 @@ public class MessagingDatabase extends Database<MessageRequest> {
 
   @Override
   public MessageRequest add(MessageRequest r) {
-    return data.put(r.reqId, r);
+    return data.put(r.reqId(), r);
   }
 
   @Override

commander/src/main/java/com/iluwatar/commander/messagingservice/MessagingService.java

@@ -44,11 +44,7 @@ public class MessagingService extends Service {
     PAYMENT_SUCCESSFUL
   }
 
-  @RequiredArgsConstructor
-  static class MessageRequest {
-    final String reqId;
-    final MessageToSend msg;
-  }
+  record MessageRequest(String reqId, MessageToSend msg) {}
 
   public MessagingService(MessagingDatabase db, Exception... exc) {
     super(db, exc);

commander/src/main/java/com/iluwatar/commander/paymentservice/PaymentService.java

@@ -51,7 +51,7 @@ public class PaymentService extends Service {
    */
 
   public String receiveRequest(Object... parameters) throws DatabaseUnavailableException {
-    //it could also be sending a userid, payment details here or something, not added here
+    //it could also be sending an userid, payment details here or something, not added here
     var id = generateId();
     var req = new PaymentRequest(id, (float) parameters[0]);
     return updateDb(req);

commander/src/main/java/com/iluwatar/commander/queue/QueueDatabase.java

@@ -25,7 +25,6 @@
 package com.iluwatar.commander.queue;
 
 import com.iluwatar.commander.Database;
-import com.iluwatar.commander.exceptions.DatabaseUnavailableException;
 import com.iluwatar.commander.exceptions.IsEmptyException;
 import java.util.ArrayList;
 import java.util.List;