3245797 - ESI - "Unknown namespace http://schemas.xmlsoap.org/soap/encoding" or "Illegal syntax: mime part is not supported" error occur during proxy generation

When trying to generate a consumer proxy through a WSDL file given by an external service provider, one of the errors below is raised and you cannot proceed with the Consumer Proxy generation:

Proxy Generation: error occurred
A library handler exception was raised
Illegal syntax: mime part is not supported

OR

Incorrect value: Unknown namespace http://schemas.xmlsoap.org/soap/encoding

SAP NetWeaver

SE80, WSDL, mime part is not supported, proxy, Proxy Generation, A library handler exception was raised, Illegal syntax, literal, Incorrect value: Unknown namespace http://schemas.xmlsoap.org/soap/encoding/, Unknown namespace, schemas.xmlsoap.org/soap/encoding , KBA , BC-DWB-PRX , Proxy Generation , BC-ESI-WS-ABA , Web Service and SOAP - ABAP , Known Error