refactor: Try and pull error message from IAM response

Author: lpatino10

src/main/java/com/ibm/cloud/sdk/core/service/exception/ServiceResponseException.java

@@ -34,6 +34,7 @@ public class ServiceResponseException extends RuntimeException {
   private static final String ERRORS_KEY = "errors";
   private static final String MESSAGE_STRING = "message";
   private static final String ERROR_STRING = "error";
+  private static final String ERROR_MESSAGE = "errorMessage";
 
   private static final Type debuggingInfoType = new TypeToken<Map<String, Object>>() { }.getType();
 
@@ -65,6 +66,8 @@ public ServiceResponseException(int statusCode, Response response) {
         this.message = jsonObject.remove(ERROR_STRING).getAsString();
       } else if (jsonObject.has(MESSAGE_STRING)) {
         this.message = jsonObject.remove(MESSAGE_STRING).getAsString();
+      } else if (jsonObject.has(ERROR_MESSAGE)) {
+        this.message = jsonObject.remove(ERROR_MESSAGE).getAsString();
       }
       this.debuggingInfo = GsonSingleton.getGson().fromJson(jsonObject, debuggingInfoType);
     } catch (final Exception e) {

src/main/java/com/ibm/cloud/sdk/core/service/security/IamTokenManager.java

@@ -17,6 +17,7 @@
 import com.ibm.cloud.sdk.core.http.HttpMediaType;
 import com.ibm.cloud.sdk.core.http.RequestBuilder;
 import com.ibm.cloud.sdk.core.http.ResponseConverter;
+import com.ibm.cloud.sdk.core.service.exception.ServiceResponseException;
 import com.ibm.cloud.sdk.core.util.CredentialUtils;
 import com.ibm.cloud.sdk.core.util.ResponseConverterUtils;
 import okhttp3.Call;
@@ -163,7 +164,7 @@ private boolean isAccessTokenExpired() {
    * if it has been at least 7 days and 1 hour since the last token was
    * retrieved.
    *
-   * @returns whether the current managed refresh token is expired or not
+   * @return whether the current managed refresh token is expired or not
    */
   private boolean isRefreshTokenExpired() {
     if (tokenData.getExpiration() == null) {
@@ -193,6 +194,12 @@ public void run() {
 
         try {
           okhttp3.Response response = call.execute();
+
+          // handle possible errors
+          if (response.code() >= 400) {
+            throw new ServiceResponseException(response.code(), response);
+          }
+
           returnToken[0] = converter.convert(response);
         } catch (IOException e) {
           LOG.severe(ERROR_MESSAGE);