In my GeoServer WMS GetCapabilities document all layers have an onlineResource parameter which ends with "wms?SERVICE=WMS&" instead of just "wms?". This has the effect that I can´t cascade my GeoServer layers with other systems as cascading is quite sensitive to irregularities.
Can anyone tell if this is normal or is it a bug in GeoServer 2.5?
Does it correspond to the OGC WMS standard?
and can I change the GetCapabilities in GeoServer per hand?
You mean that your WMS is really reading the GetCapabilities from the cascaded WMS? The servers I mostly use do not bother and they trust blindly to what is configured but I am remembering that ArcGIS server may be an exception.
However, it is acceptable to advertise a GetMap URL that is different from the base URL and even it is odd to include ?SERVICE=WMS into the onlineResourse I do not believe that it is against the standard. What is important is that the service works if the WMS parameters are added to the base URL and Geoservers do work as you can test
You can see that the SERVICE=WMS appears two times in the request but it does not make any harm. I would say that the cascading WMS is the one that does not follow the standard.
and can I change the GetCapabilities in GeoServer per hand?
No, but what you can do is take a copy of the GetCapabilities response and edit the onlineResource parameter value to just wms? for the GetMap and other operations, except the GetCapabilites which would be a reference to itself (the static file you create and host on a public web site). Then point the cascading server to the static file.
