feat: update README.md

refactor: structure test issuance provider

README.md

@@ -111,6 +111,16 @@ https://github.com/walt-id/waltid-openid4vc/blob/bd9374826d7acbd0d77d15cd2a81098
 
 #### Business logic
 
+For the business logic, implement the abstract issuance provider in `src/commonMain/kotlin/id/walt/oid4vc/providers/OpenIDCredentialIssuer.kt`, providing session and cache management, as well, as cryptographic operations for issuing credentials.
+
+* **Configuration of issuance provider**
+
+https://github.com/walt-id/waltid-openid4vc/blob/bd9374826d7acbd0d77d15cd2a81098e643eb6fa/src/jvmTest/kotlin/id/walt/oid4vc/CITestProvider.kt#L39-L56
+
+* **Simple session management example**
+
+
+
 ### Verifier
 
 #### REST endpoints

src/jvmTest/kotlin/id/walt/oid4vc/CITestProvider.kt

@@ -54,15 +54,21 @@ class CITestProvider(): OpenIDCredentialIssuer(
       )
     )
 ) {
+
+  // session management
   private val authSessions: MutableMap<String, IssuanceSession> = mutableMapOf()
+
+  override fun getSession(id: String): IssuanceSession? = authSessions[id]
+  override fun putSession(id: String, session: IssuanceSession) = authSessions.put(id, session)
+  override fun removeSession(id: String) = authSessions.remove(id)
+
+  // crypto operations and credential issuance
   private val CI_TOKEN_KEY = KeyService.getService().generate(KeyAlgorithm.RSA)
   private val CI_DID_KEY = KeyService.getService().generate(KeyAlgorithm.EdDSA_Ed25519)
   val CI_ISSUER_DID = DidService.create(DidMethod.key, CI_DID_KEY.id)
-  var deferIssuance = false
   val deferredCredentialRequests = mutableMapOf<String, CredentialRequest>()
-  override fun getSession(id: String): IssuanceSession? = authSessions[id]
-  override fun putSession(id: String, session: IssuanceSession) = authSessions.put(id, session)
-  override fun removeSession(id: String) = authSessions.remove(id)
+  var deferIssuance = false
+
   override fun signToken(target: TokenTarget, payload: JsonObject, header: JsonObject?, keyId: String?)
     = JwtService.getService().sign(keyId ?: CI_TOKEN_KEY.id, payload.toString())