Clean up IterablesChain.

* Change builder return type to Iterable<T> instead of IterableChain<T>. It is over-specified and unnecessary to state the return type so precisely.

* Optimize builder for cases where we add 0 or 1 iterables to the chain. In this case, we can simply return the underlying iterables without adding wrappers.

* Extract DedupingIterable, it doesn't have anything to do with IterablesChain and is only used in one place

RELNOTES: None
PiperOrigin-RevId: 193363048

1 files changed, 1 insertions, 1 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/collect/CollectionUtilsTest.java b/src/test/java/com/google/devtools/build/lib/collect/CollectionUtilsTest.java
index 9f8b3770a1..40d4db2cdd 100644
--- a/src/test/java/com/google/devtools/build/lib/collect/CollectionUtilsTest.java
+++ b/src/test/java/com/google/devtools/build/lib/collect/CollectionUtilsTest.java
@@ -64,7 +64,7 @@ public class CollectionUtilsTest {
     NestedSet<Integer> ns2 = NestedSetBuilder.<Integer>linkOrder().add(1).add(2).add(3).build();
     assertThat(CollectionUtils.isImmutable(ns2)).isTrue();
 
-    IterablesChain<Integer> chain = IterablesChain.<Integer>builder().addElement(1).build();
+    Iterable<Integer> chain = IterablesChain.<Integer>builder().addElement(1).build();
 
     assertThat(CollectionUtils.isImmutable(chain)).isTrue();