Add log on ProtectedTransportIntent compilation error

Change-Id: Ie6ca008fc88f0168e4ce81129e73d235f8a9c1a1
diff --git a/core/net/src/main/java/org/onosproject/net/intent/impl/compiler/ProtectedTransportIntentCompiler.java b/core/net/src/main/java/org/onosproject/net/intent/impl/compiler/ProtectedTransportIntentCompiler.java
index 94d1138..e3c7d02 100644
--- a/core/net/src/main/java/org/onosproject/net/intent/impl/compiler/ProtectedTransportIntentCompiler.java
+++ b/core/net/src/main/java/org/onosproject/net/intent/impl/compiler/ProtectedTransportIntentCompiler.java
@@ -482,6 +482,7 @@
             .reduce(Sets::intersection);
 
          if (!common.isPresent() || common.get().isEmpty()) {
+             log.error("No common label available for: {}", path);
              throw new IntentCompilationException("No common label available for: " + path);
          }
          return common.get();