docs: add comments.

Author: blakeli0

sdk-platform-java/api-common-java/src/main/java/com/google/api/pathtemplate/PathTemplate.java

@@ -313,8 +313,11 @@ public Set<String> getResourceLiterals() {
           continue;
         }
         if (inBinding) {
+          // This is for extracting "projects" and "locations" from named binding
+          // {name=projects/*/locations/*}
           canonicalSegments.add(value);
         } else if (i + 1 < segments.size() && segments.get(i + 1).kind() == SegmentKind.BINDING) {
+          // This is for regular cases projects/{project}/locations/{location}
           canonicalSegments.add(value);
         }
       }
@@ -330,6 +333,9 @@ public Set<String> getResourceLiterals() {
    */
   // For example, projects/{project} is a literal/binding pair. {bar=projects/*/locations/*/bars/*}
   // is a named binding.
+  // If a template is /compute/v1/projects/{project}/locations/{location}, known resources are
+  // "projects" and "locations", the canonical resource name is
+  // projects/{project}/locations/{location}. See unit tests for all cases.
   public String getCanonicalResourceName(Set<String> knownResources) {
     if (knownResources == null) {
       return "";

sdk-platform-java/api-common-java/src/test/java/com/google/api/pathtemplate/PathTemplateTest.java

@@ -903,6 +903,15 @@ void testGetResourceLiterals_simplePath() {
         .containsExactly("projects", "locations", "widgets");
   }
 
+  @Test
+  void testGetResourceLiterals_multipleLiterals() {
+    PathTemplate template =
+        PathTemplate.create(
+            "/compute/v1/projects/{project}/global/locations/{location}/widgets/{widget}");
+    Truth.assertThat(template.getResourceLiterals())
+        .containsExactly("projects", "locations", "widgets");
+  }
+
   @Test
   void testGetResourceLiterals_regexPath() {
     PathTemplate template =