>From https://beam.apache.org/documentation/programming-guide/#side-inputs
> If the side input has multiple trigger firings, Beam uses the value from the latest trigger firing. This is particularly useful if you use a side input with a single global window and specify a trigger. I have this sub-pipeline: -> GlobalWindow (triggering AfterProcessingTime.pastFirstElementInPane) -> Combine.perKey (Max) -> View.asMap ...which I use as a side input. But I get a "Duplicate values for <key>" error (DirectRunner). (Stack trace below.) But the only way for duplicate keys to come out of the global window is via multiple triggers. What am I missing? === java.lang.IllegalArgumentException: Duplicate values for :ihop at org.apache.beam.sdk.values.PCollectionViews$MapViewFn.apply(PCollectionViews.java:397) at org.apache.beam.sdk.values.PCollectionViews$MapViewFn.apply(PCollectionViews.java:373) at org.apache.beam.runners.direct.SideInputContainer$SideInputContainerSideInputReader.get(SideInputContainer.java:261) at org.apache.beam.repackaged.direct_java.runners.core.SimpleDoFnRunner.sideInput(SimpleDoFnRunner.java:247) at org.apache.beam.repackaged.direct_java.runners.core.SimpleDoFnRunner.access$900(SimpleDoFnRunner.java:74) at org.apache.beam.repackaged.direct_java.runners.core.SimpleDoFnRunner$DoFnProcessContext.sideInput(SimpleDoFnRunner.java:548)
