Avoid to have unexpected exception on status code 429 TooManyRequests

build.gradle

@@ -82,3 +82,4 @@ dependencies {
 tasks.named('test') { task ->
     useJUnitPlatform()
 }
+targetCompatibility = JavaVersion.VERSION_1_8

src/main/java/org/stellar/sdk/requests/ResponseHandler.java

@@ -6,6 +6,7 @@
 import org.stellar.sdk.responses.TypedResponse;
 
 import java.io.IOException;
+import java.util.Optional;
 
 import okhttp3.Response;
 
@@ -28,7 +29,14 @@ public T handleResponse(final Response response) throws IOException, TooManyRequ
     try {
       // Too Many Requests
       if (response.code() == 429) {
-        int retryAfter = Integer.parseInt(response.header("Retry-After"));
+
+        Optional<Integer> retryAfter = Optional.empty();
+        String header = response.header("Retry-After");
+        if (header != null) {
+          try {
+            retryAfter = Optional.of(Integer.parseInt(header));
+          } catch (NumberFormatException ignored) {}
+        }
         throw new TooManyRequestsException(retryAfter);
       }
 

src/main/java/org/stellar/sdk/requests/TooManyRequestsException.java

@@ -1,21 +1,24 @@
 package org.stellar.sdk.requests;
 
+import java.util.Optional;
+
 /**
  * Exception thrown when too many requests were sent to the Horizon server.
  * @see <a href="https://developers.stellar.org/api/introduction/rate-limiting/" target="_blank">Rate Limiting</a>
  */
 public class TooManyRequestsException extends RuntimeException {
-  private int retryAfter;
+  private Optional<Integer> retryAfter;
 
-  public TooManyRequestsException(int retryAfter) {
+  public TooManyRequestsException(Optional<Integer> retryAfter) {
     super("The rate limit for the requesting IP address is over its alloted limit.");
     this.retryAfter = retryAfter;
   }
 
   /**
-   * Returns number of seconds a client should wait before sending requests again.
+   * Returns number of seconds a client should wait before sending requests again,
+   * or -1 this time is unknown.
    */
-  public int getRetryAfter() {
+  public Optional<Integer> getRetryAfter() {
     return retryAfter;
   }
 }

src/test/java/org/stellar/sdk/requests/ResponseHandlerTest.java

@@ -0,0 +1,66 @@
+package org.stellar.sdk.requests;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.IOException;
+import java.util.Optional;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import okhttp3.OkHttpClient;
+import okhttp3.mockwebserver.MockResponse;
+import okhttp3.mockwebserver.MockWebServer;
+
+public class ResponseHandlerTest {
+
+    @Test
+    public void testTooManyRequests() throws IOException, InterruptedException {
+
+        MockResponse response = new MockResponse();
+        response.setResponseCode(429);
+        response.setHeader("Retry-After", "10");
+
+        MockWebServer mockWebServer = new MockWebServer();
+        mockWebServer.start();
+        mockWebServer.enqueue(response);
+
+        OkHttpClient okHttpClient = new OkHttpClient().newBuilder().build();
+        try {
+
+            AccountsRequestBuilder.execute(okHttpClient, mockWebServer.url("/"));
+            Assert.fail();
+        } catch (TooManyRequestsException tmre) {
+            assertEquals(Optional.of(10), tmre.getRetryAfter());
+        } finally {
+
+            mockWebServer.shutdown();
+            mockWebServer.close();
+        }
+    }
+
+    @Test
+    public void testTooManyRequestsNoHeader() throws IOException, InterruptedException {
+
+        MockResponse response = new MockResponse();
+        response.setResponseCode(429);
+
+        MockWebServer mockWebServer = new MockWebServer();
+
+        mockWebServer.start();
+        mockWebServer.enqueue(response);
+
+        OkHttpClient okHttpClient = new OkHttpClient().newBuilder().build();
+
+        try {
+            AccountsRequestBuilder.execute(okHttpClient, mockWebServer.url("/"));
+            Assert.fail();
+        } catch (TooManyRequestsException tmre) {
+            assertEquals(Optional.empty(), tmre.getRetryAfter());
+        } finally {
+
+            mockWebServer.shutdown();
+            mockWebServer.close();
+        }
+    }
+}