Remove addAll for always-empty set.

If exceptionInducingTargets isn't empty, an error would have been thrown and we wouldn't have reached this return line anyway.

PiperOrigin-RevId: 444569174

src/main/java/com/google/devtools/build/lib/analysis/constraints/TopLevelConstraintSemantics.java

@@ -309,7 +309,7 @@ public Set<ConfiguredTarget> checkTargetEnvironmentRestrictions(
               .setAnalysis(Analysis.newBuilder().setCode(Code.TARGETS_MISSING_ENVIRONMENTS))
               .build());
     }
-    return ImmutableSet.copyOf(badTargets.addAll(exceptionInducingTargets.keySet()).build());
+    return badTargets.build();
   }
 
   /**