support multiple date formats

src/main/java/com/dabsquared/gitlabjenkins/GitLabMergeRequest.java

@@ -1,7 +1,12 @@
 package com.dabsquared.gitlabjenkins;
 
 import java.io.IOException;
+import java.lang.reflect.Type;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.util.Arrays;
 import java.util.Date;
+import java.util.Locale;
 
 import org.apache.commons.lang.builder.ToStringBuilder;
 import org.apache.commons.lang.builder.ToStringStyle;
@@ -10,6 +15,10 @@ import org.gitlab.api.models.GitlabProject;
 import com.google.gson.FieldNamingPolicy;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
+import com.google.gson.JsonDeserializationContext;
+import com.google.gson.JsonDeserializer;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonParseException;
 
 /**
  * Represents for WebHook payload
@@ -23,13 +32,36 @@ public class GitLabMergeRequest {
             throw new IllegalArgumentException("payload should not be null");
         }
 
-        Gson gson = new GsonBuilder().setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES).setDateFormat("yyyy-MM-dd HH:mm:ss Z").create();
+        Gson gson = new GsonBuilder()
+        .setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
+        .registerTypeAdapter(Date.class, new GitLabMergeRequest.DateSerializer())
+        .create();
         GitLabMergeRequest mergeRequest =  gson.fromJson(payload, GitLabMergeRequest.class);
         
         return mergeRequest;
     }
+    
+    private static final String[] DATE_FORMATS = new String[] {
+    	"yyyy-MM-dd HH:mm:ss Z",
+    	"yyyy-MM-dd'T'HH:mm:ss.SSSZ"
+    };
 
 
+    private static class DateSerializer implements JsonDeserializer<Date> {
+        public Date deserialize(JsonElement jsonElement, Type typeOF,
+                JsonDeserializationContext context) throws JsonParseException {
+            for (String format : DATE_FORMATS) {
+                try {
+                    return new SimpleDateFormat(format, Locale.US).parse(jsonElement.getAsString());
+                } catch (ParseException e) {
+                }
+            }
+            throw new JsonParseException("Unparseable date: \"" + jsonElement.getAsString()
+                    + "\". Supported formats: " + Arrays.toString(DATE_FORMATS));
+        }
+    }
+    
+    
 
     public GitLabMergeRequest() {
     }