anchor.diff:  <1> Create call credentials with basic scheme
   <2> Create service stub
   <3> Attach call credentials to the call
  -
  ++
   `AuthHeader` could also be built with bespoke authorization scheme :
  -
  ++
   [source,java]
   ----
    AuthHeader
  
positive.code: <2> Intercept channel
  <3> Provide token generator function (Please refer to link:grpc-spring-boot-starter-demo/src/test/java/org/lognet/springboot/grpc/auth/JwtAuthBaseTest.java[for example].)
  
  * Per-call :
  +
  [source,java]
  ----
  
negative.code: 
  By adding `io.github.lognet:grpc-client-spring-boot-starter` dependency to your *java grpc client* application you can easily configure per-channel or per-call credentials :
  
  Per-channel::
  +
  [source,java]
  ----
  