Some more cleanup.

--
MOS_MIGRATED_REVID=87942730
diff --git a/src/test/java/com/google/devtools/build/lib/shell/CommandLargeInputsTest.java b/src/test/java/com/google/devtools/build/lib/shell/CommandLargeInputsTest.java
index 06d4f9a..8ffacd1 100644
--- a/src/test/java/com/google/devtools/build/lib/shell/CommandLargeInputsTest.java
+++ b/src/test/java/com/google/devtools/build/lib/shell/CommandLargeInputsTest.java
@@ -121,11 +121,11 @@
     ByteArrayOutputStream out = new ByteArrayOutputStream();
     ByteArrayOutputStream err = new ByteArrayOutputStream();
     command.execute(Command.NO_INPUT, Command.NO_OBSERVER, out, err);
-    StringBuffer expectedOut = new StringBuffer();
-    StringBuffer expectedErr = new StringBuffer();
+    StringBuilder expectedOut = new StringBuilder();
+    StringBuilder expectedErr = new StringBuilder();
     for (int i = 0; i < 1000; i++) {
-      expectedOut.append("OUT").append(Integer.toString(i)).append("\n");
-      expectedErr.append("ERR").append(Integer.toString(i)).append("\n");
+      expectedOut.append("OUT").append(i).append("\n");
+      expectedErr.append("ERR").append(i).append("\n");
     }
     assertEquals(expectedOut.toString(), out.toString("UTF-8"));
     assertEquals(expectedErr.toString(), err.toString("UTF-8"));