Rework exception handling to attach original exception. (#125)

* Rework exception handling so that original exception is attached to GitlabApiException.
* Simplify exception handling, but keeping relevant data.
* Remove unused imports

src/main/java/org/gitlab4j/api/webhook/WebHookManager.java

 
 package org.gitlab4j.api.webhook;
 
-import java.io.IOException;
 import java.io.InputStreamReader;
 import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
@@ -15,9 +14,6 @@ import org.gitlab4j.api.HookManager;
 import org.gitlab4j.api.utils.HttpRequestUtils;
 import org.gitlab4j.api.utils.JacksonJson;
 
-import com.fasterxml.jackson.core.JsonParseException;
-import com.fasterxml.jackson.databind.JsonMappingException;
-
 /**
  * This class provides a handler for processing GitLab WebHook callouts.
  */
@@ -81,7 +77,6 @@ public class WebHookManager extends HookManager {
             throw new GitLabApiException(message);
         }
 
-        String errorMessage = null;
         try {
 
             Event event;
@@ -98,22 +93,10 @@ public class WebHookManager extends HookManager {
 
             fireEvent(event);
 
-        } catch (JsonParseException jpe) {
-            errorMessage = jpe.getMessage();
-            LOG.warning("Error parsing JSON data, error=" + errorMessage);
-        } catch (JsonMappingException jme) {
-            errorMessage = jme.getMessage();
-            LOG.warning("Error mapping JSON data, error=" + errorMessage);
-        } catch (IOException ioe) {
-            errorMessage = ioe.getMessage();
-            LOG.warning("Error reading JSON data, error=" + errorMessage);
         } catch (Exception e) {
-            errorMessage = e.getMessage();
-            LOG.warning("Unexpected error reading JSON data, error=" + errorMessage);
+            LOG.warning("Error parsing JSON data, exception=" + e.getClass().getSimpleName() + ", error=" + e.getMessage());
+            throw new GitLabApiException(e);
         }
-
-        if (errorMessage != null)
-            throw new GitLabApiException(errorMessage);
     }
 
     /**