1 files changed, 12 insertions, 31 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/collect/CollectionUtils.java b/src/main/java/com/google/devtools/build/lib/collect/CollectionUtils.java
index 341e750b87..dc33350d6e 100644
--- a/src/main/java/com/google/devtools/build/lib/collect/CollectionUtils.java
+++ b/src/main/java/com/google/devtools/build/lib/collect/CollectionUtils.java
@@ -13,14 +13,17 @@
 // limitations under the License.
 package com.google.devtools.build.lib.collect;
 
-import static com.google.common.collect.Sets.newEnumSet;
+import static com.google.common.collect.ImmutableList.toImmutableList;
+import static java.util.stream.Collectors.toCollection;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Maps;
 import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.util.Preconditions;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Comparator;
 import java.util.EnumSet;
@@ -28,6 +31,7 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 
 /**
@@ -106,13 +110,7 @@ public final class CollectionUtils {
    */
   @SuppressWarnings("unchecked")
   public static <T> ImmutableList<T> asListWithoutNulls(T... elements) {
-    ImmutableList.Builder<T> builder = ImmutableList.builder();
-    for (T element : elements) {
-      if (element != null) {
-        builder.add(element);
-      }
-    }
-    return builder.build();
+    return Arrays.stream(elements).filter(Objects::nonNull).collect(toImmutableList());
   }
 
   /**
@@ -139,11 +137,7 @@ public final class CollectionUtils {
    * Given an iterable, returns an immutable iterable with the same contents.
    */
   public static <T> Iterable<T> makeImmutable(Iterable<T> iterable) {
-    if (isImmutable(iterable)) {
-      return iterable;
-    } else {
-      return ImmutableList.copyOf(iterable);
-    }
+    return isImmutable(iterable) ? iterable : ImmutableList.copyOf(iterable);
   }
 
   /**
@@ -178,14 +172,9 @@ public final class CollectionUtils {
   public static <T extends Enum<T>> EnumSet<T> fromBits(int value, Class<T> clazz) {
     T[] elements = clazz.getEnumConstants();
     Preconditions.checkArgument(elements.length <= 32);
-    ArrayList<T> result = new ArrayList<>();
-    for (T element : elements) {
-      if ((value & (1 << element.ordinal())) != 0) {
-        result.add(element);
-      }
-    }
-
-    return newEnumSet(result, clazz);
+    return Arrays.stream(elements)
+        .filter(element -> (value & (1 << element.ordinal())) != 0)
+        .collect(toCollection(() -> EnumSet.noneOf(clazz)));
   }
 
   /**
@@ -200,11 +189,7 @@ public final class CollectionUtils {
    */
   public static <KEY_1, KEY_2, VALUE> ImmutableMap<KEY_1, ImmutableMap<KEY_2, VALUE>> toImmutable(
       Map<KEY_1, Map<KEY_2, VALUE>> map) {
-    ImmutableMap.Builder<KEY_1, ImmutableMap<KEY_2, VALUE>> builder = ImmutableMap.builder();
-    for (Map.Entry<KEY_1, Map<KEY_2, VALUE>> entry : map.entrySet()) {
-      builder.put(entry.getKey(), ImmutableMap.copyOf(entry.getValue()));
-    }
-    return builder.build();
+    return ImmutableMap.copyOf(Maps.transformValues(map, ImmutableMap::copyOf));
   }
 
   /**
@@ -212,10 +197,6 @@ public final class CollectionUtils {
    */
   public static <KEY_1, KEY_2, VALUE> Map<KEY_1, Map<KEY_2, VALUE>> copyOf(
       Map<KEY_1, ? extends Map<KEY_2, VALUE>> map) {
-    Map<KEY_1, Map<KEY_2, VALUE>> result = new HashMap<>();
-    for (Map.Entry<KEY_1, ? extends Map<KEY_2, VALUE>> entry : map.entrySet()) {
-      result.put(entry.getKey(), new HashMap<>(entry.getValue()));
-    }
-    return result;
+    return new HashMap<>(Maps.transformValues(map, HashMap::new));
   }
 }