The buildViolation and buildValidation methods should handle exceptions if the fields are null

formattedValidation.addProperty("validationId", validation.get("validationId").getAsString());
formattedValidation.addProperty("validationTimestamp", validation.get("validationTimestamp").getAsString());
formattedValidation.addProperty("modelVersionId", validation.get("entity").getAsJsonObject().get("poa-event").getAsJsonObject().get("modelVersionId").getAsString());
formattedValidation.addProperty("modelInvariantId", validation.get("entity").getAsJsonObject().get("poa-event").getAsJsonObject().get("modelInvariantId").getAsString());
formattedValidation.addProperty("serviceInstanceId",validation.get("entity").getAsJsonObject().get("poa-event").getAsJsonObject().get("serviceInstanceId").getAsString());
formattedValidation.addProperty("requestId",validation.get("entity").getAsJsonObject().get("poa-event").getAsJsonObject().get("xTransactionId").getAsString());
formattedValidation.addProperty("client",validation.get("entity").getAsJsonObject().get("poa-event").getAsJsonObject().get("xFromAppId").getAsString());
formattedValidation.addProperty("result", validation.get("result").getAsString());