added response headers to GitLabApiException

src/main/java/org/gitlab4j/api/GitLabApiException.java

@@ -10,7 +10,9 @@
 import javax.ws.rs.core.MediaType;
 import javax.ws.rs.core.Response;
 import javax.ws.rs.core.Response.StatusType;
+import javax.ws.rs.core.MultivaluedMap;
 
+import java.util.Objects;
 import org.gitlab4j.api.utils.JacksonJson;
 
 import com.fasterxml.jackson.databind.JsonNode;
@@ -26,7 +28,8 @@ public class GitLabApiException extends Exception {
     private int httpStatus;
     private String message;
     private Map<String, List<String>> validationErrors;
-
+    private MultivaluedMap<String, String> headers;
+
     /**
      * Create a GitLabApiException instance with the specified message.
      *
@@ -59,6 +62,7 @@ public GitLabApiException(Response response) {
         super();
         statusInfo = response.getStatusInfo();
         httpStatus = response.getStatus();
+        headers = response.getStringHeaders();
 
         if (response.hasEntity()) {
 
@@ -87,7 +91,7 @@ public GitLabApiException(Response response) {
                             while(fields.hasNext()) {
 
                                 Entry<String, JsonNode> field = fields.next();
-                                String fieldName = field.getKey();                                
+                                String fieldName = field.getKey();
                                 List<String> values = new ArrayList<>();
                                 validationErrors.put(fieldName, values);
                                 for (JsonNode value : field.getValue()) {
@@ -186,16 +190,25 @@ public boolean hasValidationErrors() {
     }
 
     /**
-     * Returns a Map&lt;String, List&lt;String&gt;&gt; instance containing validation errors if this GitLabApiException 
+     * Returns a Map&lt;String, List&lt;String&gt;&gt; instance containing validation errors if this GitLabApiException
      * was caused by validation errors on the GitLab server, otherwise returns null.
      *
-     * @return a Map&lt;String, List&lt;String&gt;&gt; instance containing validation errors if this GitLabApiException 
+     * @return a Map&lt;String, List&lt;String&gt;&gt; instance containing validation errors if this GitLabApiException
      * was caused by validation errors on the GitLab server, otherwise returns null
      */
     public Map<String, List<String>> getValidationErrors() {
         return (validationErrors);
     }
 
+    /**
+     * Returns the response headers. Returns null if the causing error was not a response related exception.
+     *
+     * @return the response headers or null.
+     */
+    public final MultivaluedMap<String, String> getHeaders() {
+        return (headers);
+    }
+
     @Override
     public int hashCode() {
         final int prime = 31;
@@ -204,6 +217,7 @@ public int hashCode() {
         result = prime * result + ((message == null) ? 0 : message.hashCode());
         result = prime * result + ((statusInfo == null) ? 0 : statusInfo.hashCode());
         result = prime * result + ((validationErrors == null) ? 0 : validationErrors.hashCode());
+        result = prime * result + ((headers == null) ? 0 : headers.hashCode());
         return result;
     }
 
@@ -248,6 +262,10 @@ public boolean equals(Object obj) {
             return false;
         }
 
+        if (!Objects.equals(this.headers, other.headers)) {
+            return false;
+        }
+
         return true;
     }
 }

src/test/java/org/gitlab4j/api/TestGitLabApiException.java

@@ -84,6 +84,8 @@ public void testNotFoundError() throws GitLabApiException {
             assertFalse(gae.hasValidationErrors());
             assertEquals(404, gae.getHttpStatus());
             assertTrue(gae.getMessage().contains("404"));
+            assertFalse(gae.getHeaders().isEmpty());
+            assertTrue(gae.getHeaders().containsKey("X-Request-Id"), () -> "headers contains key 'X-Request-Id'. Available keys: " + String.join(", ", gae.getHeaders().keySet()));
         }
     }