When running a Spring Boot 2.4.3 project with WebFlux and Thymeleaf to render some HTML pages, BlockHound detects blocking calls when the HTML Pages are rendered.

I am running with JDK 11 on Windows 10.

I attachment a sample program to reproduce the problem. If the test class is run, this error is shown:

2021-03-05 19:37:38.199 ERROR 3284 --- [ctor-http-nio-4] a.w.r.e.AbstractErrorWebExceptionHandler : [831b8141-1] 500 Server Error for HTTP GET "/hello"

reactor.blockhound.BlockingOperationError: Blocking call! java.io.RandomAccessFile#readBytes
at java.base/java.io.RandomAccessFile.readBytes(RandomAccessFile.java) ~[na:na]
Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException:
Error has been observed at the following site(s):
|_ checkpoint ? Handler eu.xenit.test.spring.reactor.webflux.blockhound.ThymeLeafController#hello(String, Model) [DispatcherHandler]
|_ checkpoint ? HTTP GET "/hello" [ExceptionHandlingWebHandler]
Stack trace:
at java.base/java.io.RandomAccessFile.readBytes(RandomAccessFile.java) ~[na:na]
at java.base/java.io.RandomAccessFile.read(RandomAccessFile.java:406) ~[na:na]
at java.base/java.io.RandomAccessFile.readFully(RandomAccessFile.java:470) ~[na:na]
at java.base/java.util.zip.ZipFile$Source.readFullyAt(ZipFile.java:1304) ~[na:na]
at java.base/java.util.zip.ZipFile$ZipFileInputStream.initDataOffset(ZipFile.java:998) ~[na:na]
at java.base/java.util.zip.ZipFile$ZipFileInputStream.read(ZipFile.java:1013) ~[na:na]
at java.base/java.util.zip.ZipFile$ZipFileInflaterInputStream.fill(ZipFile.java:468) ~[na:na]
at java.base/java.util.zip.InflaterInputStream.read(InflaterInputStream.java:159) ~[na:na]
at java.base/java.io.InputStream.readNBytes(InputStream.java:490) ~[na:na]
at java.base/java.util.jar.JarFile.getBytes(JarFile.java:805) ~[na:na]
at java.base/java.util.jar.JarFile.checkForSpecialAttributes(JarFile.java:1005) ~[na:na]
at java.base/java.util.jar.JarFile.isMultiRelease(JarFile.java:388) ~[na:na]
at java.base/java.util.jar.JarFile.getEntry(JarFile.java:507) ~[na:na]
at java.base/sun.net.www.protocol.jar.URLJarFile.getEntry(URLJarFile.java:131) ~[na:na]
at java.base/sun.net.www.protocol.jar.JarURLConnection.connect(JarURLConnection.java:137) ~[na:na]
at java.base/sun.net.www.protocol.jar.JarURLConnection.getInputStream(JarURLConnection.java:155) ~[na:na]
at java.base/java.net.URL.openStream(URL.java:1139) ~[na:na]
at java.base/java.lang.ClassLoader.getResourceAsStream(ClassLoader.java:1738) ~[na:na]
at org.thymeleaf.util.ClassLoaderUtils.findResourceAsStream(ClassLoaderUtils.java:355) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
at org.thymeleaf.util.ClassLoaderUtils.loadResourceAsStream(ClassLoaderUtils.java:324) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
at org.thymeleaf.Thymeleaf.(Thymeleaf.java:77) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
at org.thymeleaf.ConfigurationPrinterHelper.printConfiguration(ConfigurationPrinterHelper.java:88) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
at org.thymeleaf.TemplateEngine.initialize(TemplateEngine.java:346) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
at org.thymeleaf.TemplateEngine.getConfiguration(TemplateEngine.java:406) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
at org.thymeleaf.spring5.view.reactive.ThymeleafReactiveView.render(ThymeleafReactiveView.java:334) ~[thymeleaf-spring5-3.0.12.RELEASE.jar:3.0.12.RELEASE]
at org.springframework.web.reactive.result.view.ViewResolutionResultHandler.renderWith(ViewResolutionResultHandler.java:340) ~[spring-webflux-5.3.4.jar:5.3.4]
at org.springframework.web.reactive.result.view.ViewResolutionResultHandler.render(ViewResolutionResultHandler.java:328) ~[spring-webflux-5.3.4.jar:5.3.4]

spring-reactor-webflux-thymeleaf-blockhound.zip