我在表达式中随机出现此错误。无法找到根本原因。
此处payload.SupplierId始终为null。我用流量变量字段值设置它。
异常堆栈是：
1. object is not an instance of declaring class (java.lang.IllegalArgumentException)
sun.reflect.NativeMethodAccessorImpl:-2 (null)
2. unable to bind property (java.lang.RuntimeException)
org.mvel2.optimizers.impl.refl.nodes.SetterAccessor:43 (null)
3. Execution of the expression "payload.SupplierId = flowVars.SupplierRequestData.SupplierId" failed. (org.mule.api.expression.ExpressionRuntimeException)
org.mule.el.mvel.MVELExpressionLanguage:213 (http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/api/expression/ExpressionRuntimeException.html)
4. Execution of the expression "payload.SupplierId = flowVars.SupplierRequestData.SupplierId" failed. (org.mule.api.expression.ExpressionRuntimeException). Message payload is of type: SupplierResponse (org.mule.api.MessagingException)
org.mule.execution.ExceptionToMessagingExceptionExecutionInterceptor:35 (http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/api/MessagingException.html)