Add a null check in ProxyConfiguration to avoid a NullPointerException when calling toBuilder (#2907)

* Add a null check in ProxyConfiguration to avoid a NullPointerException when calling toBuilder

Co-authored-by: Ito <[email protected]>

Author: debora-ito

.changes/next-release/bugfix-AWSSDKforJavav2-8ec6c2e.json

@@ -0,0 +1,6 @@
+{
+    "category": "AWS SDK for Java v2", 
+    "contributor": "", 
+    "type": "bugfix", 
+    "description": "Add null check for nonProxyHosts in Apache HTTP Client ProxyConfiguration."
+}

http-clients/apache-client/src/main/java/software/amazon/awssdk/http/apache/ProxyConfiguration.java

@@ -365,7 +365,7 @@ public void setNtlmWorkstation(String ntlmWorkstation) {
 
         @Override
         public Builder nonProxyHosts(Set<String> nonProxyHosts) {
-            this.nonProxyHosts = new HashSet<>(nonProxyHosts);
+            this.nonProxyHosts = nonProxyHosts != null ? new HashSet<>(nonProxyHosts) : null;
             return this;
         }
 

http-clients/apache-client/src/test/java/software/amazon/awssdk/http/apache/ProxyConfigurationTest.java

@@ -105,6 +105,18 @@ public void testProxyConfigurationWithSystemPropertyEnabled() throws Exception {
         assertThat(config.username()).isEqualTo("user");
     }
 
+    @Test
+    public void testProxyConfigurationWithoutNonProxyHosts_toBuilder_shouldNotThrowNPE() {
+        ProxyConfiguration proxyConfiguration =
+            ProxyConfiguration.builder()
+                              .endpoint(URI.create("http://localhost:4321"))
+                              .username("username")
+                              .password("password")
+                              .build();
+
+        assertThat(proxyConfiguration.toBuilder()).isNotNull();
+    }
+
     private static void clearProxyProperties() {
         System.clearProperty("http.proxyHost");
         System.clearProperty("http.proxyPort");