chore: fix error response and rest client (#754)

Author: sbansla

src/main/java/com/sendgrid/exception/ApiErrorResponse.java

@@ -1,10 +1,9 @@
 package com.sendgrid.exception;
 
-import com.sun.net.httpserver.Headers;
+
 import lombok.Getter;
 import org.apache.http.Header;
 
-import java.util.Map;
 
 public class ApiErrorResponse extends RuntimeException {
     @Getter
@@ -17,7 +16,7 @@ public class ApiErrorResponse extends RuntimeException {
     private Header[] headers;
 
     public ApiErrorResponse(Integer statusCode, String statusMessage, Object error, Header[] headers) {
-        super(statusMessage);
+        super("An error has occurred");
         this.statusCode = statusCode;
         this.statusMessage = statusMessage;
         this.error = error;

src/main/java/com/sendgrid/http/ApiKeyRestClient.java

@@ -42,7 +42,18 @@ public Response request(final Request request) {
         }
         logRequest(request);
 
-        return null;
+        Response response = httpClient.makeRequest(request);
+
+        if (logger.isDebugEnabled()) {
+            logger.debug("status code: {}", response.getStatusCode());
+            org.apache.http.Header[] responseHeaders = response.getHeaders();
+            logger.debug("response headers:");
+            for (int i = 0; i < responseHeaders.length; i++) {
+                logger.debug("responseHeader: {}", responseHeaders[i]);
+            }
+        }
+
+        return response;
     }