the CropSerializer.serializer method probably needs to check if

croprules are null (from the database retrieval) before attempting for
iteration to serialize.

src/main/java/org/genesys2/server/servlet/controller/rest/serialization/CropSerializer.java

@@ -17,6 +17,7 @@
 package org.genesys2.server.servlet.controller.rest.serialization;
 
 import java.io.IOException;
+import java.util.List;
 
 import org.apache.commons.lang.StringUtils;
 import org.genesys2.server.model.impl.Crop;
@@ -42,11 +43,15 @@ public class CropSerializer extends JsonSerializer<Crop> {
 			if (StringUtils.isNotBlank(crop.getI18n()))
 				jgen.writeObjectField("i18n", crop.getI18n());
 
-			jgen.writeArrayFieldStart("rules");
-			for (CropRule cropRule : crop.getCropRules()) {
-				jgen.writeObject(cropRule);
+			List<CropRule> croprules = crop.getCropRules() ;
+			if(croprules != null) {
+				jgen.writeArrayFieldStart("rules");
+	
+				for (CropRule cropRule : croprules ) {
+					jgen.writeObject(cropRule);
+				}
+				jgen.writeEndArray();
 			}
-			jgen.writeEndArray();
 
 			jgen.writeEndObject();
 		}