Not detected call to `Files.readString(path)`

Expected Behavior

public static void main(String[] args) {
    BlockHound.install();
    Mono.fromCallable(() -> {
        try {
            return Files.readString(testFilePath);
        } catch (IOException e) {
            throw new RuntimeException("Could not read file: " + testFilePath, e);
        }
    })
            .subscribeOn(Schedulers.parallel())
            .block();
    // Expected blocking call error
}

Actual Behavior

BlockHound does not detect call Files.readString(path).

Steps to Reproduce

I created small project to test this issue.

Your Environment

• Reactor version(s) used: 3.4.5
• JVM version: OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.7+10, mixed mode)
• OS and version: Linux 5.8.0-49-generic 20.04.1-Ubuntu x86_64

Start with the reproduction in test/src/test/java/com/coditory/sandbox/BlockingSamplesSpec.java and the Files.readString(path) call shown in the issue. Trace how BlockHound.install() handles this call on Schedulers.parallel(), then add coverage showing that the blocking call produces the expected error.