allow arbitrary metric prefixes (#1440)

(cherry picked from commit 69360e9)

Author: sebright2

CHANGELOG.md

@@ -1,4 +1,6 @@
 ## Unreleased
+- Allow users to report metrics for their registered domain (using custom prefix). This could be a
+  breaking change if you have custom prefix without (registered) domain.
 
 ## 0.16.0 - 2018-09-14
 - Add APIs to register gRPC client and server views separately.

exporters/stats/stackdriver/src/main/java/io/opencensus/exporter/stats/stackdriver/StackdriverExporterWorker.java

@@ -68,7 +68,6 @@ final class StackdriverExporterWorker implements Runnable {
 
   @VisibleForTesting static final String DEFAULT_DISPLAY_NAME_PREFIX = "OpenCensus/";
   @VisibleForTesting static final String CUSTOM_METRIC_DOMAIN = "custom.googleapis.com/";
-  @VisibleForTesting static final String EXTERNAL_METRIC_DOMAIN = "external.googleapis.com/";
 
   @VisibleForTesting
   static final String CUSTOM_OPENCENSUS_DOMAIN = CUSTOM_METRIC_DOMAIN + "opencensus/";
@@ -252,11 +251,10 @@ static String getDomain(@javax.annotation.Nullable String metricNamePrefix) {
     if (Strings.isNullOrEmpty(metricNamePrefix)) {
       domain = CUSTOM_OPENCENSUS_DOMAIN;
     } else {
-      if (metricNamePrefix.startsWith(CUSTOM_METRIC_DOMAIN)
-          || metricNamePrefix.startsWith(EXTERNAL_METRIC_DOMAIN)) {
-        domain = metricNamePrefix;
+      if (!metricNamePrefix.endsWith("/")) {
+        domain = metricNamePrefix + '/';
       } else {
-        domain = CUSTOM_METRIC_DOMAIN + metricNamePrefix + '/';
+        domain = metricNamePrefix;
       }
     }
     return domain;

exporters/stats/stackdriver/src/test/java/io/opencensus/exporter/stats/stackdriver/StackdriverExporterWorkerTest.java

@@ -110,8 +110,6 @@ public void setUp() {
   public void testConstants() {
     assertThat(StackdriverExporterWorker.MAX_BATCH_EXPORT_SIZE).isEqualTo(200);
     assertThat(StackdriverExporterWorker.CUSTOM_METRIC_DOMAIN).isEqualTo("custom.googleapis.com/");
-    assertThat(StackdriverExporterWorker.EXTERNAL_METRIC_DOMAIN)
-        .isEqualTo("external.googleapis.com/");
     assertThat(StackdriverExporterWorker.CUSTOM_OPENCENSUS_DOMAIN)
         .isEqualTo("custom.googleapis.com/opencensus/");
     assertThat(StackdriverExporterWorker.DEFAULT_DISPLAY_NAME_PREFIX).isEqualTo("OpenCensus/");
@@ -283,8 +281,7 @@ public void getDomain() {
         .isEqualTo("custom.googleapis.com/myorg/");
     assertThat(StackdriverExporterWorker.getDomain("external.googleapis.com/prometheus/"))
         .isEqualTo("external.googleapis.com/prometheus/");
-    assertThat(StackdriverExporterWorker.getDomain("myorg"))
-        .isEqualTo("custom.googleapis.com/myorg/");
+    assertThat(StackdriverExporterWorker.getDomain("myorg")).isEqualTo("myorg/");
   }
 
   @Test