Add more logging to exception

We are seeing reports of an exception triggered due to unknown entries being
present in the sandbox base. Without actually knowing what those
files/directories are it is hard to know the next steps, for example if more
entries should be added to the allowlist SANDBOX_BASE_PERSISTENT_DIRS or if the
precondition check should be removed altogether.

This change adds more logging to get the names of the entries

RELNOTES:none
PiperOrigin-RevId: 621118864
Change-Id: Ie606f12a4148490d2c218ef5ba84605218e4f919

src/main/java/com/google/devtools/build/lib/sandbox/SandboxModule.java

@@ -17,7 +17,7 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.ImmutableList.toImmutableList;
 
-import com.google.common.base.Preconditions;
+import com.google.common.base.Joiner;
 import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
@@ -526,13 +526,19 @@ public void cleanStarting(@SuppressWarnings("unused") CleanStartingEvent event)
    */
   private static void checkSandboxBaseTopOnlyContainsPersistentDirs(Path sandboxBase) {
     try {
-      Preconditions.checkState(
-          SANDBOX_BASE_PERSISTENT_DIRS.containsAll(
-              sandboxBase.getDirectoryEntries().stream()
-                  .map(Path::getBaseName)
-                  .collect(toImmutableList())),
-          "Found unexpected files in sandbox base. Please report this in"
-              + " https://github.com/bazelbuild/bazel/issues.");
+      ImmutableList<String> directoryEntries =
+          sandboxBase.getDirectoryEntries().stream()
+              .map(Path::getBaseName)
+              .collect(toImmutableList());
+      if (!SANDBOX_BASE_PERSISTENT_DIRS.containsAll(directoryEntries)) {
+        StringBuilder message =
+            new StringBuilder(
+                "Found unexpected entries in sandbox base. Please report this in"
+                    + " https://github.com/bazelbuild/bazel/issues.");
+        message.append(" The entries are: ");
+        Joiner.on(", ").appendTo(message, directoryEntries);
+        throw new IllegalStateException(message.toString());
+      }
     } catch (IOException e) {
       logger.atWarning().withCause(e).log("Failed to clean up sandbox base %s", sandboxBase);
     }