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This follows google/xplat@f7a56b3 That commit does additionally add `@Nullable` to the `InputStream in` constructor parameters. It looks like a null `in` leads to a stream that doesn't work unless you later modify `FilterInputStream.in` directly, as [the xplat copy documents](google/xplat@f7a56b3#diff-f21cbb1ece57585a6b018af66249cc68cf16f32fbfc25fdecd2c47dc567abcc3R43-R44). On the one hand, this is no different from its superclass `FilterInputStream`, where we [included `@Nullable`](https://github.com/jspecify/jdk/blob/cf198c06e3bd59572304f866b5cbf70781112f55/src/java.base/share/classes/java/io/FilterInputStream.java#L57-L60). On the other hand, `FilterInputStream` specifically documents that passing `null` is an intended use case, and we've seen people pass `null` in practice with the intent of modifying the `in` field later. We haven't seen that with `PushbackInputStream`, even in the rare instances in which the class is subclassed.
wmdietl
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Mar 23, 2026
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wmdietl
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In the xplat version, I see lots of null checks for buf.
In this version, most places assume that buf is non-null and directly dereference it.
Only close sets it back to null, so it does make sense to make the field Nullable.
carrerabenjamin55-svg
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Mar 29, 2026
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This follows google/xplat@f7a56b3
That commit does additionally add
@Nullableto theInputStream inconstructor parameters. It looks like a null
inleads to a stream thatdoesn't work unless you later modify
FilterInputStream.indirectly, asthe xplat copy
documents.
On the one hand, this is no different from its superclass
FilterInputStream, where we included@Nullable.On the other hand,
FilterInputStreamspecifically documents thatpassing
nullis an intended use case, and we've seen people passnullin practice with the intent of modifying theinfield later. Wehaven't seen that with
PushbackInputStream, even in the rare instancesin which the class is subclassed.