bazel syntax: rename SkylarkNestedSet to Depset

The new name matches the Bazel documentation, whereas
NestedSet is a Blaze internal. Also, it is shorter.

Also: tweak its class doc comment.
All other changes are mechanical.
PiperOrigin-RevId: 281824680
diff --git a/src/test/java/com/google/devtools/build/lib/skylark/SkylarkDefinedAspectsTest.java b/src/test/java/com/google/devtools/build/lib/skylark/SkylarkDefinedAspectsTest.java
index 5314287..12f75ae 100644
--- a/src/test/java/com/google/devtools/build/lib/skylark/SkylarkDefinedAspectsTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skylark/SkylarkDefinedAspectsTest.java
@@ -45,8 +45,8 @@
 import com.google.devtools.build.lib.rules.java.JavaConfiguration;
 import com.google.devtools.build.lib.rules.objc.ObjcProtoProvider;
 import com.google.devtools.build.lib.skyframe.AspectValue;
+import com.google.devtools.build.lib.syntax.Depset;
 import com.google.devtools.build.lib.syntax.Sequence;
-import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
 import com.google.devtools.build.lib.vfs.FileSystemUtils;
 import java.util.Arrays;
 import org.junit.Before;
@@ -292,18 +292,18 @@
     ConfiguredAspect configuredAspect = aspectValue.getConfiguredAspect();
     assertThat(configuredAspect).isNotNull();
     Object names = configuredAspect.get("target_labels");
-    assertThat(names).isInstanceOf(SkylarkNestedSet.class);
+    assertThat(names).isInstanceOf(Depset.class);
     assertThat(
             transform(
-                ((SkylarkNestedSet) names).toCollection(),
+                ((Depset) names).toCollection(),
                 o -> {
                   assertThat(o).isInstanceOf(Label.class);
                   return o.toString();
                 }))
         .containsExactly("//test:xxx", "//test:yyy");
     Object ruleKinds = configuredAspect.get("rule_kinds");
-    assertThat(ruleKinds).isInstanceOf(SkylarkNestedSet.class);
-    assertThat(((SkylarkNestedSet) ruleKinds).toCollection()).containsExactly("java_library");
+    assertThat(ruleKinds).isInstanceOf(Depset.class);
+    assertThat(((Depset) ruleKinds).toCollection()).containsExactly("java_library");
   }
 
   @Test
@@ -349,12 +349,14 @@
     ConfiguredAspect configuredAspect = aspectValue.getConfiguredAspect();
     assertThat(configuredAspect).isNotNull();
     Object nameSet = configuredAspect.get("target_labels");
-    ImmutableList<String> names = ImmutableList.copyOf(transform(
-        ((SkylarkNestedSet) nameSet).toCollection(),
-        o -> {
-          assertThat(o).isInstanceOf(Label.class);
-          return ((Label) o).getName();
-        }));
+    ImmutableList<String> names =
+        ImmutableList.copyOf(
+            transform(
+                ((Depset) nameSet).toCollection(),
+                o -> {
+                  assertThat(o).isInstanceOf(Label.class);
+                  return ((Label) o).getName();
+                }));
 
     assertThat(names).containsAtLeast("xxx", "yyy");
     // Third is the C++ toolchain; its name changes between Blaze and Bazel.
@@ -594,10 +596,10 @@
     assertThat(getLabelsToBuild(analysisResult)).containsExactly("//test:xxx");
     ConfiguredTarget target = analysisResult.getTargetsToBuild().iterator().next();
     Object names = target.get("rule_deps");
-    assertThat(names).isInstanceOf(SkylarkNestedSet.class);
+    assertThat(names).isInstanceOf(Depset.class);
     assertThat(
             transform(
-                ((SkylarkNestedSet) names).toCollection(),
+                ((Depset) names).toCollection(),
                 o -> {
                   assertThat(o).isInstanceOf(Label.class);
                   return o.toString();
@@ -1640,7 +1642,7 @@
   private void buildTargetAndCheckRuleInfo(String... expectedLabels) throws Exception {
     AnalysisResult result = update(ImmutableList.<String>of(), "//test:r2");
     ConfiguredTarget configuredTarget = result.getTargetsToBuild().iterator().next();
-    SkylarkNestedSet ruleInfoValue = (SkylarkNestedSet) configuredTarget.get("rule_info");
+    Depset ruleInfoValue = (Depset) configuredTarget.get("rule_info");
     assertThat(ruleInfoValue.getSet(String.class))
         .containsExactlyElementsIn(Arrays.asList(expectedLabels));
   }
@@ -1712,8 +1714,7 @@
         "main_rule(name = 'main', deps = [':rbin', ':rgen'])");
     AnalysisResult analysisResult = update(ImmutableList.<String>of(), "//foo:main");
     ConfiguredTarget target = analysisResult.getTargetsToBuild().iterator().next();
-    NestedSet<Artifact> aspectFiles =
-        ((SkylarkNestedSet) target.get("aspect_files")).getSet(Artifact.class);
+    NestedSet<Artifact> aspectFiles = ((Depset) target.get("aspect_files")).getSet(Artifact.class);
     assertThat(transform(aspectFiles, Artifact::getFilename))
         .containsExactly("aspect-output-rbin", "aspect-output-rgen");
     for (Artifact aspectFile : aspectFiles) {
@@ -1900,10 +1901,10 @@
     ConfiguredAspect configuredAspect = aspectValue.getConfiguredAspect();
     assertThat(configuredAspect).isNotNull();
     Object names = configuredAspect.get("target_labels");
-    assertThat(names).isInstanceOf(SkylarkNestedSet.class);
+    assertThat(names).isInstanceOf(Depset.class);
     assertThat(
             transform(
-                ((SkylarkNestedSet) names).toCollection(),
+                ((Depset) names).toCollection(),
                 o -> {
                   assertThat(o).isInstanceOf(Label.class);
                   return ((Label) o).getName();
@@ -2582,7 +2583,7 @@
     SkylarkKey pCollector =
         new SkylarkKey(Label.parseAbsolute("//test:aspect.bzl", ImmutableMap.of()), "PCollector");
     StructImpl collector = (StructImpl) configuredAspect.get(pCollector);
-    assertThat(((SkylarkNestedSet) collector.getValue("visited")).toCollection())
+    assertThat(((Depset) collector.getValue("visited")).toCollection())
         .containsExactly(
             Label.parseAbsolute("//test:referenced_from_aspect_only", ImmutableMap.of()),
             Label.parseAbsolute("//test:bar", ImmutableMap.of()),
diff --git a/src/test/java/com/google/devtools/build/lib/skylark/SkylarkIntegrationTest.java b/src/test/java/com/google/devtools/build/lib/skylark/SkylarkIntegrationTest.java
index 433b989..91c8041 100644
--- a/src/test/java/com/google/devtools/build/lib/skylark/SkylarkIntegrationTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skylark/SkylarkIntegrationTest.java
@@ -55,8 +55,8 @@
 import com.google.devtools.build.lib.skyframe.PackageFunction;
 import com.google.devtools.build.lib.skyframe.SkyFunctions;
 import com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction;
+import com.google.devtools.build.lib.syntax.Depset;
 import com.google.devtools.build.lib.syntax.Sequence;
-import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
 import com.google.devtools.build.lib.syntax.Starlark;
 import com.google.devtools.build.lib.syntax.StarlarkList;
 import com.google.devtools.build.lib.vfs.FileSystemUtils;
@@ -228,7 +228,7 @@
         OutputGroupInfo.get(getConfiguredTarget("//test/skylark:lib"))
             .getOutputGroup(OutputGroupInfo.HIDDEN_TOP_LEVEL);
     ConfiguredTarget myTarget = getConfiguredTarget("//test/skylark:my");
-    SkylarkNestedSet result = (SkylarkNestedSet) getMyInfoFromTarget(myTarget).getValue("result");
+    Depset result = (Depset) getMyInfoFromTarget(myTarget).getValue("result");
     assertThat(result.getSet(Artifact.class)).containsExactlyElementsIn(hiddenTopLevelArtifacts);
     assertThat(OutputGroupInfo.get(myTarget).getOutputGroup("my_group"))
         .containsExactlyElementsIn(hiddenTopLevelArtifacts);
@@ -254,7 +254,7 @@
         OutputGroupInfo.get(getConfiguredTarget("//test/skylark:lib"))
             .getOutputGroup(OutputGroupInfo.HIDDEN_TOP_LEVEL);
     ConfiguredTarget myTarget = getConfiguredTarget("//test/skylark:my");
-    SkylarkNestedSet result = (SkylarkNestedSet) getMyInfoFromTarget(myTarget).getValue("result");
+    Depset result = (Depset) getMyInfoFromTarget(myTarget).getValue("result");
     assertThat(result.getSet(Artifact.class)).containsExactlyElementsIn(hiddenTopLevelArtifacts);
     assertThat(OutputGroupInfo.get(myTarget).getOutputGroup("my_group"))
         .containsExactlyElementsIn(hiddenTopLevelArtifacts);
@@ -288,7 +288,7 @@
             .getOutputGroup(OutputGroupInfo.HIDDEN_TOP_LEVEL);
     ConfiguredTarget myTarget = getConfiguredTarget("//test/skylark:my");
     StructImpl myInfo = getMyInfoFromTarget(myTarget);
-    SkylarkNestedSet result = (SkylarkNestedSet) myInfo.getValue("result");
+    Depset result = (Depset) myInfo.getValue("result");
     assertThat(result.getSet(Artifact.class)).containsExactlyElementsIn(hiddenTopLevelArtifacts);
     assertThat(OutputGroupInfo.get(myTarget).getOutputGroup("my_group"))
         .containsExactlyElementsIn(hiddenTopLevelArtifacts);
@@ -322,7 +322,7 @@
         OutputGroupInfo.get(getConfiguredTarget("//test/skylark:lib"))
             .getOutputGroup(OutputGroupInfo.HIDDEN_TOP_LEVEL);
     ConfiguredTarget myTarget = getConfiguredTarget("//test/skylark:my");
-    SkylarkNestedSet result = (SkylarkNestedSet) getMyInfoFromTarget(myTarget).getValue("result");
+    Depset result = (Depset) getMyInfoFromTarget(myTarget).getValue("result");
     assertThat(result.getSet(Artifact.class)).containsExactlyElementsIn(hiddenTopLevelArtifacts);
     assertThat(OutputGroupInfo.get(myTarget).getOutputGroup("my_group"))
         .containsExactlyElementsIn(hiddenTopLevelArtifacts);
@@ -351,7 +351,7 @@
         OutputGroupInfo.get(getConfiguredTarget("//test/skylark:lib"))
             .getOutputGroup(OutputGroupInfo.HIDDEN_TOP_LEVEL);
     ConfiguredTarget myTarget = getConfiguredTarget("//test/skylark:my");
-    SkylarkNestedSet result = (SkylarkNestedSet) getMyInfoFromTarget(myTarget).getValue("result");
+    Depset result = (Depset) getMyInfoFromTarget(myTarget).getValue("result");
     assertThat(result.getSet(Artifact.class)).containsExactlyElementsIn(hiddenTopLevelArtifacts);
     assertThat(OutputGroupInfo.get(myTarget).getOutputGroup("my_group"))
         .containsExactlyElementsIn(hiddenTopLevelArtifacts);
@@ -380,7 +380,7 @@
         OutputGroupInfo.get(getConfiguredTarget("//test/skylark:lib"))
             .getOutputGroup(OutputGroupInfo.HIDDEN_TOP_LEVEL);
     ConfiguredTarget myTarget = getConfiguredTarget("//test/skylark:my");
-    SkylarkNestedSet result = (SkylarkNestedSet) getMyInfoFromTarget(myTarget).getValue("result");
+    Depset result = (Depset) getMyInfoFromTarget(myTarget).getValue("result");
     assertThat(result.getSet(Artifact.class)).containsExactlyElementsIn(hiddenTopLevelArtifacts);
     assertThat(OutputGroupInfo.get(myTarget).getOutputGroup("my_group"))
         .containsExactlyElementsIn(hiddenTopLevelArtifacts);
@@ -834,7 +834,7 @@
 
     assertThat(
             ActionsTestUtil.baseArtifactNames(
-                ((SkylarkNestedSet) getMyInfoFromTarget(target).getValue("provider_key"))
+                ((Depset) getMyInfoFromTarget(target).getValue("provider_key"))
                     .getSet(Artifact.class)))
         .containsExactly("a.txt");
   }
diff --git a/src/test/java/com/google/devtools/build/lib/skylark/SkylarkRuleClassFunctionsTest.java b/src/test/java/com/google/devtools/build/lib/skylark/SkylarkRuleClassFunctionsTest.java
index ad00cd9..9d650c2 100644
--- a/src/test/java/com/google/devtools/build/lib/skylark/SkylarkRuleClassFunctionsTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skylark/SkylarkRuleClassFunctionsTest.java
@@ -47,12 +47,12 @@
 import com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction;
 import com.google.devtools.build.lib.skylark.util.SkylarkTestCase;
 import com.google.devtools.build.lib.syntax.ClassObject;
+import com.google.devtools.build.lib.syntax.Depset;
 import com.google.devtools.build.lib.syntax.Dict;
 import com.google.devtools.build.lib.syntax.EvalException;
 import com.google.devtools.build.lib.syntax.EvalUtils;
 import com.google.devtools.build.lib.syntax.Mutability;
 import com.google.devtools.build.lib.syntax.ParserInput;
-import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
 import com.google.devtools.build.lib.syntax.StarlarkFile;
 import com.google.devtools.build.lib.syntax.StarlarkList;
 import com.google.devtools.build.lib.syntax.SyntaxError;
@@ -1260,7 +1260,7 @@
   @Test
   public void testNsetGoodCompositeItem() throws Exception {
     exec("def func():", "  return depset([struct(a='a')])", "s = func()");
-    Collection<?> result = ((SkylarkNestedSet) lookup("s")).toCollection();
+    Collection<?> result = ((Depset) lookup("s")).toCollection();
     assertThat(result).hasSize(1);
     assertThat(result.iterator().next()).isInstanceOf(StructImpl.class);
   }
diff --git a/src/test/java/com/google/devtools/build/lib/skylark/SkylarkRuleContextTest.java b/src/test/java/com/google/devtools/build/lib/skylark/SkylarkRuleContextTest.java
index fb134dd..83b6949 100644
--- a/src/test/java/com/google/devtools/build/lib/skylark/SkylarkRuleContextTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skylark/SkylarkRuleContextTest.java
@@ -47,10 +47,10 @@
 import com.google.devtools.build.lib.rules.java.JavaSourceJarsProvider;
 import com.google.devtools.build.lib.rules.python.PyProviderUtils;
 import com.google.devtools.build.lib.skylark.util.SkylarkTestCase;
+import com.google.devtools.build.lib.syntax.Depset;
 import com.google.devtools.build.lib.syntax.Dict;
 import com.google.devtools.build.lib.syntax.Mutability;
 import com.google.devtools.build.lib.syntax.Sequence;
-import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
 import com.google.devtools.build.lib.syntax.Starlark;
 import com.google.devtools.build.lib.syntax.StarlarkList;
 import com.google.devtools.build.lib.testutil.TestRuleClassProvider;
@@ -1924,8 +1924,8 @@
     update("action1", eval("ruleContext.attr.dep[Actions].by_file[file1]"));
     update("action2", eval("ruleContext.attr.dep[Actions].by_file[file2]"));
 
-    assertThat(eval("action1.inputs")).isInstanceOf(SkylarkNestedSet.class);
-    assertThat(eval("action1.outputs")).isInstanceOf(SkylarkNestedSet.class);
+    assertThat(eval("action1.inputs")).isInstanceOf(Depset.class);
+    assertThat(eval("action1.outputs")).isInstanceOf(Depset.class);
 
     assertThat(eval("action1.argv")).isEqualTo(Starlark.NONE);
     assertThat(eval("action2.content")).isEqualTo(Starlark.NONE);
diff --git a/src/test/java/com/google/devtools/build/lib/skylark/SkylarkRuleImplementationFunctionsTest.java b/src/test/java/com/google/devtools/build/lib/skylark/SkylarkRuleImplementationFunctionsTest.java
index 83d6fec..e6615d0 100644
--- a/src/test/java/com/google/devtools/build/lib/skylark/SkylarkRuleImplementationFunctionsTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skylark/SkylarkRuleImplementationFunctionsTest.java
@@ -58,11 +58,11 @@
 import com.google.devtools.build.lib.skylarkinterface.Param;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkGlobalLibrary;
+import com.google.devtools.build.lib.syntax.Depset;
 import com.google.devtools.build.lib.syntax.EvalException;
 import com.google.devtools.build.lib.syntax.EvalUtils;
 import com.google.devtools.build.lib.syntax.Printer;
 import com.google.devtools.build.lib.syntax.Sequence;
-import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
 import com.google.devtools.build.lib.syntax.Starlark;
 import com.google.devtools.build.lib.syntax.StarlarkList;
 import com.google.devtools.build.lib.syntax.StarlarkThread;
@@ -750,7 +750,7 @@
         "    executable = 'dummy',",
         ")");
     assertArtifactFilenames(
-        ((SkylarkNestedSet) lookup("inputs")).getSet(Artifact.class),
+        ((Depset) lookup("inputs")).getSet(Artifact.class),
         "mytool.sh",
         "mytool",
         "foo_Smytool" + OsUtils.executableExtension() + "-runfiles",
@@ -992,7 +992,7 @@
   public void testFilesForRuleConfiguredTarget() throws Exception {
     setRuleContext(createRuleContext("//foo:foo"));
     Object result = eval("ruleContext.attr.srcs[0].files");
-    assertThat(ActionsTestUtil.baseNamesOf(((SkylarkNestedSet) result).getSet(Artifact.class)))
+    assertThat(ActionsTestUtil.baseNamesOf(((Depset) result).getSet(Artifact.class)))
         .isEqualTo("a.txt");
   }
 
@@ -1072,7 +1072,7 @@
         .containsExactly(
             "File:[/workspace[source]]test/run.file", "File:[/workspace[source]]test/run2.file");
 
-    assertThat(myInfo.getValue("rule_files")).isInstanceOf(SkylarkNestedSet.class);
+    assertThat(myInfo.getValue("rule_files")).isInstanceOf(Depset.class);
     assertThat(myInfo.getValue("rule_files_to_run")).isInstanceOf(FilesToRunProvider.class);
     assertThat(myInfo.getValue("rule_file_executable")).isEqualTo(Starlark.NONE);
   }
@@ -1152,7 +1152,7 @@
         .containsExactly(
             "File:[/workspace[source]]test/run.file", "File:[/workspace[source]]test/run2.file");
 
-    assertThat(myInfo.getValue("rule_files")).isInstanceOf(SkylarkNestedSet.class);
+    assertThat(myInfo.getValue("rule_files")).isInstanceOf(Depset.class);
     assertThat(myInfo.getValue("rule_files_to_run")).isInstanceOf(FilesToRunProvider.class);
   }
 
@@ -1243,7 +1243,7 @@
                 String::valueOf))
         .isEmpty();
 
-    assertThat(myInfo.getValue("file_files")).isInstanceOf(SkylarkNestedSet.class);
+    assertThat(myInfo.getValue("file_files")).isInstanceOf(Depset.class);
     assertThat(myInfo.getValue("file_files_to_run")).isInstanceOf(FilesToRunProvider.class);
   }
 
@@ -1796,7 +1796,7 @@
   public void testFilesForFileConfiguredTarget() throws Exception {
     setRuleContext(createRuleContext("//foo:bar"));
     Object result = eval("ruleContext.attr.srcs[0].files");
-    assertThat(ActionsTestUtil.baseNamesOf(((SkylarkNestedSet) result).getSet(Artifact.class)))
+    assertThat(ActionsTestUtil.baseNamesOf(((Depset) result).getSet(Artifact.class)))
         .isEqualTo("libjl.jar");
   }