Extract Proxy-Authorization header name as constant

Co-authored-by: chrjohn <6644028+chrjohn@users.noreply.github.com>

Author: Copilot

quickfixj-core/src/main/java/quickfix/mina/ProtocolFactory.java

@@ -57,6 +57,8 @@ public class ProtocolFactory {
 
     public final static int SOCKET = 0;
     public final static int VM_PIPE = 1;
+    
+    public final static String PROXY_AUTHORIZATION_HEADER = "Proxy-Authorization";
 
     public static String getTypeString(int type) {
         switch (type) {
@@ -176,7 +178,7 @@ private static ProxyRequest createHttpProxyRequest(InetSocketAddress address,
             Map<String, List<String>> headers = new HashMap<>();
             String credentials = proxyUser + ":" + proxyPassword;
             String encodedCredentials = Base64.getEncoder().encodeToString(credentials.getBytes(StandardCharsets.UTF_8));
-            headers.put("Proxy-Authorization", Collections.singletonList("Basic " + encodedCredentials));
+            headers.put(PROXY_AUTHORIZATION_HEADER, Collections.singletonList("Basic " + encodedCredentials));
             req.setHeaders(headers);
         }
 

quickfixj-core/src/test/java/quickfix/mina/ProtocolFactoryTest.java

@@ -37,6 +37,7 @@
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
+import static quickfix.mina.ProtocolFactory.PROXY_AUTHORIZATION_HEADER;
 
 public class ProtocolFactoryTest {
 
@@ -69,9 +70,9 @@ public void shouldSetBasicAuthorizationHeaderForHttpProxy() throws ConfigError {
 
         Map<String, List<String>> headers = request.getHeaders();
         assertNotNull("Headers should not be null", headers);
-        assertTrue("Headers should contain Proxy-Authorization", headers.containsKey("Proxy-Authorization"));
+        assertTrue("Headers should contain Proxy-Authorization", headers.containsKey(PROXY_AUTHORIZATION_HEADER));
 
-        List<String> authHeaders = headers.get("Proxy-Authorization");
+        List<String> authHeaders = headers.get(PROXY_AUTHORIZATION_HEADER);
         assertNotNull("Proxy-Authorization header should not be null", authHeaders);
         assertEquals("Should have exactly one Proxy-Authorization header", 1, authHeaders.size());
 
@@ -100,7 +101,7 @@ public void shouldNotSetAuthorizationHeaderForNTLMAuthentication() throws Config
         Map<String, List<String>> headers = request.getHeaders();
         // NTLM requires multi-step handshake, so Proxy-Authorization header should not be set upfront
         assertTrue("Headers should be null or not contain Proxy-Authorization for NTLM", 
-                   headers == null || !headers.containsKey("Proxy-Authorization"));
+                   headers == null || !headers.containsKey(PROXY_AUTHORIZATION_HEADER));
 
         // Verify NTLM properties are set correctly for the MINA proxy handler to use
         Map<String, String> props = request.getProperties();
@@ -124,6 +125,6 @@ public void shouldNotSetAuthorizationHeaderWhenCredentialsNotProvided() throws C
         Map<String, List<String>> headers = request.getHeaders();
         // Headers should either be null or not contain Proxy-Authorization
         assertTrue("Headers should be null or empty when no credentials provided", 
-                   headers == null || !headers.containsKey("Proxy-Authorization"));
+                   headers == null || !headers.containsKey(PROXY_AUTHORIZATION_HEADER));
     }
 }