Fix the crash on older Android versions without desugaring

src/main/java/com/pusher/client/connection/impl/PusherEventHandler.java

@@ -0,0 +1,12 @@
+package com.pusher.client.connection.impl;
+
+import com.pusher.client.channel.PusherEvent;
+
+/**
+ * Receives events from the connection.
+ * <p>
+ * Used instead of java.util.function.Consumer, which isn't available before Android 7 (API 24).
+ */
+public interface PusherEventHandler {
+    void handle(PusherEvent event);
+}

src/main/java/com/pusher/client/connection/websocket/WebSocketConnection.java

@@ -6,6 +6,7 @@
 import com.pusher.client.connection.ConnectionState;
 import com.pusher.client.connection.ConnectionStateChange;
 import com.pusher.client.connection.impl.InternalConnection;
+import com.pusher.client.connection.impl.PusherEventHandler;
 import com.pusher.client.util.Factory;
 
 import org.java_websocket.handshake.ServerHandshake;
@@ -20,7 +21,6 @@
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
-import java.util.function.Consumer;
 import java.util.logging.Logger;
 
 import javax.net.ssl.SSLException;
@@ -42,7 +42,7 @@ public class WebSocketConnection implements InternalConnection, WebSocketListene
 
     private volatile ConnectionState state = ConnectionState.DISCONNECTED;
     private WebSocketClientWrapper underlyingConnection;
-    private final Consumer<PusherEvent> eventHandler;
+    private final PusherEventHandler eventHandler;
     private String socketId;
     private int reconnectAttempts = 0;
     private volatile Future<?> reconnectTimer;
@@ -54,7 +54,7 @@ public WebSocketConnection(
             int maxReconnectionAttempts,
             int maxReconnectionGap,
             final Proxy proxy,
-            final Consumer<PusherEvent> eventHandler,
+            final PusherEventHandler eventHandler,
             final Factory factory
     ) throws URISyntaxException {
         webSocketUri = new URI(url);
@@ -167,7 +167,7 @@ private void handleEvent(final PusherEvent event) {
         } else if (event.getEventName().equals("pusher:error")) {
             handleError(event);
         }
-        eventHandler.accept(event);
+        eventHandler.handle(event);
     }
 
     @SuppressWarnings("rawtypes")

src/main/java/com/pusher/client/util/Factory.java

@@ -10,6 +10,7 @@
 import com.pusher.client.channel.impl.PrivateChannelImpl;
 import com.pusher.client.channel.impl.PrivateEncryptedChannelImpl;
 import com.pusher.client.connection.impl.InternalConnection;
+import com.pusher.client.connection.impl.PusherEventHandler;
 import com.pusher.client.connection.websocket.WebSocketClientWrapper;
 import com.pusher.client.connection.websocket.WebSocketConnection;
 import com.pusher.client.connection.websocket.WebSocketListener;
@@ -23,7 +24,6 @@
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ThreadFactory;
-import java.util.function.Consumer;
 
 import javax.net.ssl.SSLException;
 
@@ -55,7 +55,7 @@ public class Factory {
     public synchronized InternalConnection getConnection(
             final String apiKey,
             final PusherOptions options,
-            final Consumer<PusherEvent> eventHandler
+            final PusherEventHandler eventHandler
     ) {
         if (connection == null) {
             try {

src/test/java/com/pusher/client/EndToEndTest.java

@@ -9,6 +9,7 @@
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
+import com.pusher.client.connection.impl.PusherEventHandler;
 import com.pusher.client.channel.PusherEvent;
 import com.pusher.client.channel.impl.ChannelManager;
 import com.pusher.client.connection.ConnectionEventListener;
@@ -33,7 +34,6 @@
 
 import java.net.Proxy;
 import java.net.URI;
-import java.util.function.Consumer;
 
 @RunWith(MockitoJUnitRunner.class)
 public class EndToEndTest {
@@ -57,7 +57,7 @@ public class EndToEndTest {
     private ChannelAuthorizer mockChannelAuthorizer;
 
     @Mock
-    private Consumer<PusherEvent> mockEventHandler;
+    private PusherEventHandler mockEventHandler;
 
     @Mock
     private ConnectionEventListener mockConnectionEventListener;
@@ -117,7 +117,7 @@ public WebSocketClientWrapper answer(final InvocationOnMock invocation) throws T
                         }
                 );
 
-        when(factory.getConnection(eq(API_KEY), eq(pusherOptions), any(Consumer.class))).thenReturn(connection);
+        when(factory.getConnection(eq(API_KEY), eq(pusherOptions), any(PusherEventHandler.class))).thenReturn(connection);
 
         when(factory.getChannelManager())
                 .thenAnswer(

src/test/java/com/pusher/client/PusherTest.java

@@ -10,6 +10,7 @@
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
+import com.pusher.client.connection.impl.PusherEventHandler;
 import com.pusher.client.channel.ChannelEventListener;
 import com.pusher.client.channel.PresenceChannelEventListener;
 import com.pusher.client.channel.PrivateChannelEventListener;
@@ -33,7 +34,6 @@
 import org.mockito.runners.MockitoJUnitRunner;
 import org.mockito.stubbing.Answer;
 
-import java.util.function.Consumer;
 
 @RunWith(MockitoJUnitRunner.class)
 public class PusherTest {
@@ -88,7 +88,7 @@ public void setUp() {
                         .setChannelAuthorizer(channelAuthorizer)
                         .setUserAuthenticator(new HttpUserAuthenticator("http://user-auth.com"));
 
-        when(factory.getConnection(eq(API_KEY), any(PusherOptions.class), any(Consumer.class)))
+        when(factory.getConnection(eq(API_KEY), any(PusherOptions.class), any(PusherEventHandler.class)))
                 .thenReturn(mockConnection);
         when(factory.getChannelManager()).thenReturn(mockChannelManager);
         when(factory.newPublicChannel(PUBLIC_CHANNEL_NAME)).thenReturn(mockPublicChannel);

src/test/java/com/pusher/client/connection/websocket/WebSocketConnectionTest.java

@@ -15,6 +15,7 @@
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
+import com.pusher.client.connection.impl.PusherEventHandler;
 import com.pusher.client.channel.PusherEvent;
 import com.pusher.client.connection.ConnectionEventListener;
 import com.pusher.client.connection.ConnectionState;
@@ -39,7 +40,6 @@
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.ScheduledThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
-import java.util.function.Consumer;
 
 import javax.net.ssl.SSLException;
 
@@ -62,7 +62,7 @@ public class WebSocketConnectionTest {
     private WebSocketClientWrapper mockUnderlyingConnection;
 
     @Mock
-    private Consumer<PusherEvent> mockEventHandler;
+    private PusherEventHandler mockEventHandler;
 
     @Mock
     private ConnectionEventListener mockEventListener;
@@ -271,7 +271,7 @@ public void testReceiveUserMessagePassesMessageToEventHandler() {
         connect();
 
         connection.onMessage(INCOMING_MESSAGE);
-        // verify(mockEventHandler).accept(EVENT_NAME, INCOMING_MESSAGE);
+        // verify(mockEventHandler).handle(EVENT_NAME, INCOMING_MESSAGE);
     }
 
     @Test