How do I extract map(trim), then filter(!empty) into a method while keeping the pipeline style?

Before.java

        new StreamTextCommands()
                .streamCommandsFrom(new InputStreamReader(System.in))
                .map(String::trim)
                .filter((command) -> !command.isEmpty())
                .map(commandText -> sellOneItemController.onBarcode(commandText))
                .map(CommandResponse::render)
                .forEach(System.out::println);

FantasyAfter.java

        new StreamTextCommands()
                .streamCommandsFrom(new InputStreamReader(System.in))
                .magicApplyThatICantFind(MyClass::sanitize)
                .map(commandText -> sellOneItemController.onBarcode(commandText))
                .map(CommandResponse::render)
                .forEach(System.out::println);

// ...

    private static Stream<String> sanitize(Stream<String> uncleanCommands) {
        return uncleanCommands
                .map(String::trim)
                .filter((command) -> !command.isEmpty());
    }

UnhappyAfter.java

        sanitize(new StreamTextCommands()
                .streamCommandsFrom(new InputStreamReader(System.in)))
                .map(commandText -> sellOneItemController.onBarcode(commandText))
                .map(CommandResponse::render)
                .forEach(System.out::println);

// ...

    private static Stream<String> sanitize(Stream<String> uncleanCommands) {
        return uncleanCommands
                .map(String::trim)
                .filter((command) -> !command.isEmpty());
    }

new StreamTextCommands()
                .streamCommandsFrom(new InputStreamReader(System.in))
                .flatMap(MyClass::sanitize)
                .map(commandText -> sellOneItemController.onBarcode(commandText))
                .map(CommandResponse::render)
                .forEach(System.out::println);

private static Stream<String> sanitize(String uncleanCommand) {
     String clean = uncleanCommand.trim();   
     return clean.isEmpty() ? Stream.empty() : Stream.of(clean);
}

flatMap has a power to filter and map simultaneously, where empty stream represents removed value

Yes, @nbardiuk! I just arrived at almost the same answer myself. Thank you!

        new StreamTextCommands()
                .streamCommandsFrom(new InputStreamReader(System.in))
                .flatMap(PointOfSaleTerminal::sanitizeCommand)
                .map(commandText -> sellOneItemController.onBarcode(commandText))
                .map(CommandResponse::render)
                .forEach(System.out::println);

    private static Stream<String> sanitizeCommand(String uncleanCommand) {
        return Stream.of(uncleanCommand.trim()).filter(c -> !c.isEmpty());
    }

This illustrates the power of "making the types line up". Once I saw that flatMap turns an item into a Stream of (possibly other) things, I realized that I could apply "trim, the discard if empty" to each command. Even so, I preferred thinking of "map, then filter" as a composable transformation on Streams, but I'm willing to go with this, at least for now.