[Java] Capture exception class name if an exception occurs when processing a client command.

Author: mjpt777

aeron-driver/src/main/java/io/aeron/driver/ClientCommandAdapter.java

@@ -176,7 +176,8 @@ else if (channel.startsWith(SPY_PREFIX))
         }
         catch (final Exception ex)
         {
-            clientProxy.onError(correlationId, GENERIC_ERROR, ex.getMessage());
+            final String errorMessage = ex.getClass().getName() + " : " + ex.getMessage();
+            clientProxy.onError(correlationId, GENERIC_ERROR, errorMessage);
             recordError(ex);
         }
     }