Refactor onCloseCallback to onClose and update related usages across the codebase (#62)

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/server/Server.kt

@@ -30,7 +30,6 @@ public class ServerOptions(
  *
  * @param serverInfo Information about this server implementation (name, version).
  * @param options Configuration options for the server.
- * @param onCloseCallback A callback invoked when the server connection closes.
  */
 public open class Server(
     private val serverInfo: Implementation,
@@ -127,7 +126,6 @@ public open class Server(
 
     /**
      * Called when the server connection is closing.
-     * Invokes [onCloseCallback] if set.
      */
     override fun onClose() {
         logger.info { "Server connection closing" }

src/jvmTest/kotlin/InMemoryTransport.kt

@@ -1,6 +1,5 @@
 import io.modelcontextprotocol.kotlin.sdk.JSONRPCMessage
 import io.modelcontextprotocol.kotlin.sdk.shared.AbstractTransport
-import io.modelcontextprotocol.kotlin.sdk.shared.Transport
 
 /**
  * In-memory transport for creating clients and servers that talk to each other within the same process.

src/jvmTest/kotlin/client/InMemoryTransportTest.kt

@@ -96,11 +96,9 @@ class InMemoryTransportTest {
             clientTransport.close()
 
             assertThrows<IllegalStateException> {
-                runBlocking {
-                    clientTransport.send(
-                        InitializedNotification().toJSON()
-                    )
-                }
+                clientTransport.send(
+                    InitializedNotification().toJSON()
+                )
             }
         }
     }