fix checker framework warn for LoadingPageServer

src/main/java/ru/investbook/loadingpage/LoadingPageServer.java

@@ -22,6 +22,7 @@
 import com.sun.net.httpserver.HttpHandler;
 import com.sun.net.httpserver.HttpServer;
 import lombok.extern.slf4j.Slf4j;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import ru.investbook.BrowserHomePageOpener;
 
 import java.io.ByteArrayOutputStream;
@@ -30,51 +31,45 @@
 import java.io.OutputStream;
 import java.net.InetSocketAddress;
 
-import static java.nio.charset.StandardCharsets.*;
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static java.util.Objects.nonNull;
+import static java.util.Objects.requireNonNull;
 
 @Slf4j
 public class LoadingPageServer implements AutoCloseable{
     public static final int SERVER_PORT = 2031;
     public static final int DEFAULT_CLOSE_DELAY_SEC = 120;
 
-    private HttpServer server;
+    private volatile @Nullable HttpServer server = null;
 
     public void start() {
         try {
-            server = HttpServer.create(new InetSocketAddress(SERVER_PORT), 0);
+            HttpServer server = HttpServer.create(new InetSocketAddress(SERVER_PORT), 0);
             server.createContext("/", new LoadingPageHandler());
             server.createContext("/main-app-port", new PortHandler());
-
             server.start();
-
+            this.server = server;
             String loadingPageUrl = "http://localhost:" + SERVER_PORT + "/loading";
             BrowserHomePageOpener.open(loadingPageUrl);
         } catch (IOException e) {
             log.warn("Can't open /loading page", e);
         }
     }
 
-    public void stopAfter(int delayInSec) {
-        if (isRunning()) {
-            server.stop(delayInSec);
-            server = null;
-        }
-    }
-
-    public boolean isRunning() {
-        return server != null;
-    }
-
     @Override
     public void close() {
-        stopAfter(DEFAULT_CLOSE_DELAY_SEC);
+        if (nonNull(server)) {
+            //noinspection DataFlowIssue
+            server.stop(DEFAULT_CLOSE_DELAY_SEC);
+            server = null;
+        }
     }
 
     static class LoadingPageHandler implements HttpHandler {
         @Override
         public void handle(HttpExchange exchange) throws IOException {
             byte[] data;
-            try (InputStream in = getClass().getResourceAsStream("/templates/loading.html")) {
+            try (InputStream in = requireNonNull(getClass().getResourceAsStream("/templates/loading.html"))) {
                 ByteArrayOutputStream out = new ByteArrayOutputStream();
                 in.transferTo(out);
                 data = out.toByteArray();

src/main/java/ru/investbook/loadingpage/LoadingPageServerUtils.java

@@ -20,6 +20,7 @@
 
 import lombok.experimental.UtilityClass;
 import lombok.extern.slf4j.Slf4j;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.io.IOException;
 import java.io.InputStream;
@@ -30,6 +31,7 @@
 import java.util.Properties;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
+import static java.util.Objects.requireNonNull;
 
 @Slf4j
 @UtilityClass
@@ -66,8 +68,8 @@ private static Properties loadProperties() throws IOException {
             properties.load(reader);
         } catch (Exception e) {
             // Properties file is not found in app installation path, read default file from class path
-            try (InputStream in = LoadingPageServerUtils.class.getClassLoader().getResourceAsStream(CONF_PROPERTIES);
-                 Reader reader = new InputStreamReader(in, UTF_8)) {
+            try (@Nullable InputStream in = LoadingPageServerUtils.class.getResourceAsStream(CONF_PROPERTIES);
+                 Reader reader = new InputStreamReader(requireNonNull(in), UTF_8)) {
                 properties.load(reader);
             }
         }

src/test/java/ru/investbook/LoadingPageServerTests.java → src/test/java/ru/investbook/LoadingPageServerTest.java

@@ -26,10 +26,10 @@
 import org.mockito.junit.jupiter.MockitoExtension;
 import ru.investbook.loadingpage.LoadingPageServer;
 
-import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.times;
 
 @ExtendWith(MockitoExtension.class)
-class LoadingPageServerTests {
+class LoadingPageServerTest {
 
     private LoadingPageServer loadingPageServer;