chore: better error message when metric publish failed (#2214)

Also reduces logging when there are continuous failures (like permission denied).

Thank you for opening a Pull Request! Before submitting your PR, there are a few things you can do to make sure it goes smoothly:
- [ ] Make sure to open an issue as a [bug/issue](https://togithub.com/googleapis/java-bigtable/issues/new/choose) before writing your code!  That way we can discuss the change, evaluate designs, and agree on the general idea
- [ ] Ensure the tests and linter pass
- [ ] Code coverage does not decrease (if any source code was changed)
- [ ] Appropriate docs were updated (if necessary)
- [ ] Rollback plan is reviewed and LGTMed
- [ ] All new data plane features have a completed end to end testing plan

Fixes #<issue_number_goes_here> ☕️

If you write sample code, please follow the [samples format](
https://togithub.com/GoogleCloudPlatform/java-docs-samples/blob/main/SAMPLE_FORMAT.md).

README.md

@@ -19,7 +19,7 @@ If you are using Maven with [BOM][libraries-bom], add this to your pom.xml file:
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>libraries-bom</artifactId>
-      <version>26.37.0</version>
+      <version>26.25.0</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>

google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/data/v2/stub/metrics/BigtableCloudMonitoringExporter.java

@@ -34,6 +34,7 @@
 import com.google.api.gax.core.CredentialsProvider;
 import com.google.api.gax.core.FixedCredentialsProvider;
 import com.google.api.gax.core.NoCredentialsProvider;
+import com.google.api.gax.rpc.PermissionDeniedException;
 import com.google.auth.Credentials;
 import com.google.cloud.monitoring.v3.MetricServiceClient;
 import com.google.cloud.monitoring.v3.MetricServiceSettings;
@@ -96,6 +97,9 @@ public final class BigtableCloudMonitoringExporter implements MetricExporter {
 
   private CompletableResultCode lastExportCode;
 
+  private final AtomicBoolean bigtableExportFailureLogged = new AtomicBoolean(false);
+  private final AtomicBoolean applicationExportFailureLogged = new AtomicBoolean(false);
+
   private static final ImmutableList<String> BIGTABLE_TABLE_METRICS =
       ImmutableSet.of(
               OPERATION_LATENCIES_NAME,
@@ -227,15 +231,24 @@ private CompletableResultCode exportBigtableResourceMetrics(Collection<MetricDat
         new ApiFutureCallback<Empty>() {
           @Override
           public void onFailure(Throwable throwable) {
-            logger.log(
-                Level.WARNING,
-                "createServiceTimeSeries request failed for bigtable metrics. ",
-                throwable);
+            if (bigtableExportFailureLogged.compareAndSet(false, true)) {
+              String msg = "createServiceTimeSeries request failed for bigtable metrics.";
+              if (throwable instanceof PermissionDeniedException) {
+                msg +=
+                    String.format(
+                        " Need monitoring metric writer permission on project=%s. Follow https://cloud.google.com/bigtable/docs/client-side-metrics-setup to set up permissions.",
+                        projectName.getProject());
+              }
+              logger.log(Level.WARNING, msg, throwable);
+            }
             bigtableExportCode.fail();
           }
 
           @Override
           public void onSuccess(Empty empty) {
+            // When an export succeeded reset the export failure flag to false so if there's a
+            // transient failure it'll be logged.
+            bigtableExportFailureLogged.set(false);
             bigtableExportCode.succeed();
           }
         },
@@ -295,15 +308,24 @@ private CompletableResultCode exportApplicationResourceMetrics(
           new ApiFutureCallback<Empty>() {
             @Override
             public void onFailure(Throwable throwable) {
-              logger.log(
-                  Level.WARNING,
-                  "createServiceTimeSeries request failed for per connection error metrics.",
-                  throwable);
+              if (applicationExportFailureLogged.compareAndSet(false, true)) {
+                String msg = "createServiceTimeSeries request failed for bigtable metrics.";
+                if (throwable instanceof PermissionDeniedException) {
+                  msg +=
+                      String.format(
+                          " Need monitoring metric writer permission on project=%s. Follow https://cloud.google.com/bigtable/docs/client-side-metrics-setup to set up permissions.",
+                          projectName.getProject());
+                }
+                logger.log(Level.WARNING, msg, throwable);
+              }
               exportCode.fail();
             }
 
             @Override
             public void onSuccess(Empty empty) {
+              // When an export succeeded reset the export failure flag to false so if there's a
+              // transient failure it'll be logged.
+              applicationExportFailureLogged.set(false);
               exportCode.succeed();
             }
           },