fix(ocpp201): MessageInfoType::state is optional (#159)

Author: j-white

src/tests/schema_validation/v2_0_1.rs

@@ -1924,7 +1924,7 @@ mod tests {
             message_info: Some(vec![MessageInfoType {
                 id: 0,
                 priority: MessagePriorityEnumType::AlwaysFront,
-                state: MessageStateEnumType::Charging,
+                state: Some(MessageStateEnumType::Charging),
                 start_date_time: Some(Utc::now()),
                 end_date_time: Some(Utc::now()),
                 transaction_id: Some("transaction_id".to_string()),
@@ -3035,7 +3035,7 @@ mod tests {
             message: MessageInfoType {
                 id: 0,
                 priority: MessagePriorityEnumType::AlwaysFront,
-                state: MessageStateEnumType::Charging,
+                state: Some(MessageStateEnumType::Charging),
                 start_date_time: Some(Utc::now()),
                 end_date_time: Some(Utc::now()),
                 transaction_id: Some("".to_string()),

src/v2_0_1/datatypes/message_info_type.rs

@@ -13,7 +13,8 @@ use crate::v2_0_1::enumerations::message_state_enum_type::MessageStateEnumType;
 pub struct MessageInfoType {
     pub id: i32,
     pub priority: MessagePriorityEnumType,
-    pub state: MessageStateEnumType,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub state: Option<MessageStateEnumType>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub start_date_time: Option<DateTime<Utc>>,
     #[serde(skip_serializing_if = "Option::is_none")]