Fixed SPI test.

Author: JonathanHenson

http-clients/aws-crt-client/src/main/java/software/amazon/awssdk/http/crt/internal/AwsCrtResponseBodyPublisher.java

@@ -248,8 +248,8 @@ protected synchronized void publishToSubscribers() {
             }
         }
 
-        // Check if Complete
-        if (queueComplete.get() && queuedBuffers.size() == 0) {
+        // Check if Complete, consider no subscriber as a completion.
+        if (queueComplete.get() && (subscriberRef.get() == null || queuedBuffers.size() == 0)) {
             completeSubscriptionExactlyOnce();
         }
     }

http-clients/aws-crt-client/src/test/java/software/amazon/awssdk/http/crt/AwsCrtHttpClientSpiVerificationTest.java

@@ -37,8 +37,8 @@
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.atomic.AtomicReference;
+
 import org.junit.After;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
@@ -239,7 +239,6 @@ public void testPutRequest() throws Exception {
         stubFor(any(urlEqualTo(pathExpect200)).withRequestBody(binaryEqualTo(expectedBody)).willReturn(aResponse().withStatus(200)));
         makePutRequest(pathExpect200, expectedBody, 200);
 
-
         String pathExpect404 = "/testPutRequest/return_404_always";
         byte[] randomBody = generateRandomBody(TEST_BODY_LEN);
         stubFor(any(urlEqualTo(pathExpect404)).willReturn(aResponse().withStatus(404)));