Clean up redundant attributes / modifiers

src/main/java/com/amplitude/Amplitude.java

@@ -6,27 +6,23 @@
 import java.util.concurrent.ExecutorService;
 
 public class Amplitude {
-  private static Map<String, Amplitude> instances = new HashMap<>();
+  private final static Map<String, Amplitude> instances = new HashMap<>();
   private final String instanceName;
   private String apiKey;
   private String serverUrl;
 
-  private AmplitudeLog logger;
+  private AmplitudeLog logger = new AmplitudeLog();
 
-  private Queue<Event> eventsToSend;
-  private boolean aboutToStartFlushing;
+  private final Queue<Event> eventsToSend = new ConcurrentLinkedQueue<>();
+  private boolean aboutToStartFlushing = false;
 
   private HttpCallMode httpCallMode;
-  private HttpCall httpCall;
-  private HttpTransport httpTransport;
+  private final HttpTransport httpTransport;
   private int eventUploadThreshold = Constants.EVENT_BUF_COUNT;
   private int eventUploadPeriodMillis = Constants.EVENT_BUF_TIME_MILLIS;
-  private Object eventQueueLock = new Object();
+  private final Object eventQueueLock = new Object();
   private Plan plan;
   private IngestionMetadata ingestionMetadata;
-  private long flushTimeout;
-  private ExecutorService retryThreadPool;
-  private ExecutorService sendThreadPool;
 
   /**
    * A dictionary of key-value pairs that represent additional instructions for server save
@@ -46,10 +42,7 @@ public class Amplitude {
    */
   private Amplitude(String name) {
     instanceName = name;
-    logger = new AmplitudeLog();
-    eventsToSend = new ConcurrentLinkedQueue<>();
-    aboutToStartFlushing = false;
-    httpTransport = new HttpTransport(httpCall, null, logger, flushTimeout, sendThreadPool, retryThreadPool);
+    httpTransport = new HttpTransport(logger);
   }
 
   /**
@@ -204,7 +197,6 @@ public Amplitude setLogger(AmplitudeLog logger) {
    * @param timeout the flush events threads timeout millis
    */
   public Amplitude setFlushTimeout(long timeout) {
-    flushTimeout = timeout;
     this.httpTransport.setFlushTimeout(timeout);
     return this;
   }
@@ -215,7 +207,6 @@ public Amplitude setFlushTimeout(long timeout) {
    * @param sendThreadPool the thread pool for sending events
    */
   public Amplitude setSendThreadPool(ExecutorService sendThreadPool) {
-    this.sendThreadPool = sendThreadPool;
     this.httpTransport.setSendThreadPool(sendThreadPool);
     return this;
   }
@@ -226,7 +217,6 @@ public Amplitude setSendThreadPool(ExecutorService sendThreadPool) {
    * @param retryThreadPool the thread pool for retrying events
    */
   public Amplitude setRetryThreadPool(ExecutorService retryThreadPool) {
-    this.retryThreadPool = retryThreadPool;
     this.httpTransport.setRetryThreadPool(retryThreadPool);
     return this;
   }
@@ -356,14 +346,13 @@ private void updateHttpCall(HttpCallMode updatedHttpCallMode) {
     httpCallMode = updatedHttpCallMode;
 
     if (updatedHttpCallMode == HttpCallMode.BATCH) {
-      httpCall =
+      httpTransport.setHttpCall(
           new HttpCall(
-              apiKey, serverUrl != null ? serverUrl : Constants.BATCH_API_URL, options, proxy);
+              apiKey, serverUrl != null ? serverUrl : Constants.BATCH_API_URL, options, proxy));
     } else {
-      httpCall =
-          new HttpCall(apiKey, serverUrl != null ? serverUrl : Constants.API_URL, options, proxy);
+      httpTransport.setHttpCall(
+          new HttpCall(apiKey, serverUrl != null ? serverUrl : Constants.API_URL, options, proxy));
     }
-    httpTransport.setHttpCall(httpCall);
   }
 
   private synchronized void scheduleFlushEvents() {

src/main/java/com/amplitude/HttpTransport.java

@@ -30,31 +30,25 @@ protected EventsRetryResult(
 
 class HttpTransport {
   // Use map to record the events are currently in retry queue.
-  private Object throttleLock = new Object();
-  private Map<String, Integer> throttledUserId = new HashMap<>();
-  private Map<String, Integer> throttledDeviceId = new HashMap<>();
+  private final Object throttleLock = new Object();
+  private final Map<String, Integer> throttledUserId = new HashMap<>();
+  private final Map<String, Integer> throttledDeviceId = new HashMap<>();
   private boolean recordThrottledId = false;
-  private Map<String, Map<String, List<Event>>> idToBuffer = new HashMap<>();
+  private final Map<String, Map<String, List<Event>>> idToBuffer = new HashMap<>();
   private int eventsInRetry = 0;
-  private Object bufferLock = new Object();
-  private Object counterLock = new Object();
-  private ExecutorService retryThreadPool;
-  private ExecutorService sendThreadPool;
-
-  private HttpCall httpCall;
-  private AmplitudeLog logger;
-  private AmplitudeCallbacks callbacks;
-  private long flushTimeout;
-
-  HttpTransport(
-      HttpCall httpCall, AmplitudeCallbacks callbacks, AmplitudeLog logger,
-      long flushTimeout, ExecutorService sendThreadPool, ExecutorService retryThreadPool) {
-    this.httpCall = httpCall;
-    this.callbacks = callbacks;
+  private final Object bufferLock = new Object();
+  private final Object counterLock = new Object();
+
+  // Managed by setters
+  private ExecutorService retryThreadPool = Executors.newFixedThreadPool(10);
+  private ExecutorService sendThreadPool = Executors.newFixedThreadPool(40);
+  private HttpCall httpCall = null;
+  private long flushTimeout = 0;
+  private AmplitudeCallbacks callbacks = null;
+  private final AmplitudeLog logger;
+
+  HttpTransport(AmplitudeLog logger) {
     this.logger = logger;
-    this.flushTimeout = flushTimeout;
-    this.retryThreadPool = (retryThreadPool == null) ? Executors.newFixedThreadPool(10) : retryThreadPool;
-    this.sendThreadPool = (sendThreadPool == null) ? Executors.newFixedThreadPool(40) : sendThreadPool;
   }
 
   public void sendEventsWithRetry(List<Event> events) {

src/test/java/com/amplitude/HttpTransportTest.java

@@ -25,7 +25,6 @@
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.CsvSource;
-import org.mockito.BDDMockito;
 import org.mockito.junit.jupiter.MockitoExtension;
 
 import com.amplitude.exception.AmplitudeInvalidAPIKeyException;
@@ -40,7 +39,7 @@ public class HttpTransportTest {
 
   @BeforeEach
   public void setUp() {
-    httpTransport = new HttpTransport(null, null, new AmplitudeLog(), 0, null, null);
+    httpTransport = new HttpTransport(new AmplitudeLog());
   }
 
   /**