3565724 - API Management or API proxy : sap-message is truncated

In API Proxy call an OData-service in on-premise backend system.
The call is in JSON-format and get an error message in response header which was assign to the body.
The error message gets cut randomly at the first comma.

The correct <Header name="sap-message"> is :
<Header name="sap-message">{"code":"ZPIC/004","message":"Article not found.","target":"","severity":"error","transition":false,"details":[]}  </Header>

Arrives to API Proxy in format:
{"code":"ZPIC/004",message":"Article not found.,target":",severity":"error,"transition":false,"details":[]}  

The wrong result/format is only observed in API proxy or API management debug screen.

• SAP Gateway (OData)
• API Management
• API Proxy

SAP Integration Suite, API Management, JSON parser, OData-service, API Proxy, response header, error message, quotation marks, comma, response truncation, response.header.sap-message.values.string , response.header.sap-message , KBA , OPU-API-OD-DT , Designtime , OPU-GW-COR , Framework , Problem