ADDITIONAL SYSTEM INFORMATION :
java version "16.0.1" 2021-04-20
Java(TM) SE Runtime Environment (build 16.0.1+9-24)
Java HotSpot(TM) 64-Bit Server VM (build 16.0.1+9-24, mixed mode, sharing)
---
ProductName: macOS
ProductVersion: 11.2.3
BuildVersion: 20D91




A DESCRIPTION OF THE PROBLEM :
Like other bugs reported with generic types inference with anonymous classes, the compiler throws an internal NPE when trying to infer the types.

Given the following method:

public <RQ, RS> Mono<RS> createAirData(final String path, final ParameterizedTypeReference<RS> parameterizedTypeReference, final RQ request) {
        return webClient.post()
                        .uri(path)
                        .bodyValue(request)
                        .retrieve()
                        .bodyToMono(parameterizedTypeReference)
                        .timeout(timeout);
    }

The following code breaks the compiler:

StepVerifier.create(createAirData(path, new ParameterizedTypeReference<>() {}, request))
                    .expectNext(response)
                    .verifyComplete();

It can be fixed by specifying the generic type explicitly (avoiding inference) or by extracting a variable so type can be inferred:

ParameterizedTypeReference<Object> parameterizedTypeReference = new ParameterizedTypeReference<>() {};
StepVerifier.create(reactiveAirDataService.createAirData(path, parameterizedTypeReference, request))
                    .expectNext(response)
                    .verifyComplete();

------------
The exception received when the type cannot be inferred:

 An exception has occurred in the compiler (16.0.1). Please file a bug against the Java compiler via the Java bug reporting page (http://bugreport.java.com) after checking the Bug Database (http://bugs.java.com) for duplicates. Include your program, the following diagnostic, and the parameters passed to the Java compiler in your report. Thank you.
[ERROR] java.lang.NullPointerException: Cannot invoke "com.sun.tools.javac.code.Type.getThrownTypes()" because "tree.meth.type" is null
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitApply(Flow.java:1383)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1745)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:57)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitApply(Flow.java:1382)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1745)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.visitSelect(TreeScanner.java:316)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCFieldAccess.accept(JCTree.java:2273)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitApply(Flow.java:1381)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1745)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.visitSelect(TreeScanner.java:316)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCFieldAccess.accept(JCTree.java:2273)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitApply(Flow.java:1381)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1745)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.visitExec(TreeScanner.java:219)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCExpressionStatement.accept(JCTree.java:1532)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:57)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitBlock(Flow.java:1131)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1047)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitMethodDef(Flow.java:1097)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:893)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitClassDef(Flow.java:1060)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:790)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.analyzeTree(Flow.java:1476)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.analyzeTree(Flow.java:1466)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow.analyzeTree(Flow.java:218)
[ERROR] at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1404)
[ERROR] at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1378)
[ERROR] at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:973)
[ERROR] at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:317)
[ERROR] at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:176)
[ERROR] at jdk.compiler/com.sun.tools.javac.Main.compile(Main.java:82)
[ERROR] at jdk.internal.reflect.GeneratedMethodAccessor59.invoke(Unknown Source)
[ERROR] at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[ERROR] at java.base/java.lang.reflect.Method.invoke(Method.java:567)
[ERROR] at org.codehaus.plexus.compiler.javac.JavacCompiler.compileInProcess0(JavacCompiler.java:626)
[ERROR] at org.codehaus.plexus.compiler.javac.JavacCompiler.compileInProcessWithProperClassloader(JavacCompiler.java:607)
[ERROR] at org.codehaus.plexus.compiler.javac.JavacCompiler.compileInProcess(JavacCompiler.java:596)
[ERROR] at org.codehaus.plexus.compiler.javac.JavacCompiler.performCompile(JavacCompiler.java:178)
[ERROR] at org.apache.maven.plugin.compiler.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:1134)
[ERROR] at org.apache.maven.plugin.compiler.TestCompilerMojo.execute(TestCompilerMojo.java:180)
[ERROR] at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:137)
[ERROR] at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:210)
[ERROR] at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:156)
[ERROR] at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:148)
[ERROR] at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:117)
[ERROR] at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:81)
[ERROR] at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:56)
[ERROR] at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
[ERROR] at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:305)
[ERROR] at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:192)
[ERROR] at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:105)
[ERROR] at org.apache.maven.cli.MavenCli.execute(MavenCli.java:957)
[ERROR] at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:289)
[ERROR] at org.apache.maven.cli.MavenCli.main(MavenCli.java:193)
[ERROR] at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[ERROR] at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78)
[ERROR] at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[ERROR] at java.base/java.lang.reflect.Method.invoke(Method.java:567)
[ERROR] at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:282)
[ERROR] at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:225)
[ERROR] at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:406)
[ERROR] at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:347)




STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Create a method similar to createAirData (receiving a generic interface)
2. Call some kind of builder/pipeline that receives the output of the method, similar to the StepVerifier.create used in the description (example bellow) and finish it with a method that loses the value of T

---
StepVerifier methods:

static <T> FirstStep<T> create(Publisher<? extends T> publisher) {
return create(publisher, Long.MAX_VALUE);
}

---
FirstStep methods:

    Step<T> expectNext(T t);

    //The return type Duration causes the type to be lost and seems to be the reason of the NPE
    Duration verifyComplete();


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
It should compile with no issues
ACTUAL -
 An exception has occurred in the compiler (16.0.1). Please file a bug against the Java compiler via the Java bug reporting page (http://bugreport.java.com) after checking the Bug Database (http://bugs.java.com) for duplicates. Include your program, the following diagnostic, and the parameters passed to the Java compiler in your report. Thank you.
[ERROR] java.lang.NullPointerException: Cannot invoke "com.sun.tools.javac.code.Type.getThrownTypes()" because "tree.meth.type" is null
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitApply(Flow.java:1383)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1745)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:57)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitApply(Flow.java:1382)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1745)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.visitSelect(TreeScanner.java:316)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCFieldAccess.accept(JCTree.java:2273)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitApply(Flow.java:1381)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1745)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.visitSelect(TreeScanner.java:316)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCFieldAccess.accept(JCTree.java:2273)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitApply(Flow.java:1381)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1745)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.visitExec(TreeScanner.java:219)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCExpressionStatement.accept(JCTree.java:1532)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:57)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitBlock(Flow.java:1131)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1047)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitMethodDef(Flow.java:1097)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:893)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.visitClassDef(Flow.java:1060)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:790)
[ERROR] at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:440)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.analyzeTree(Flow.java:1476)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow$FlowAnalyzer.analyzeTree(Flow.java:1466)
[ERROR] at jdk.compiler/com.sun.tools.javac.comp.Flow.analyzeTree(Flow.java:218)
[ERROR] at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1404)
[ERROR] at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1378)
[ERROR] at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:973)
[ERROR] at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:317)
[ERROR] at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:176)
[ERROR] at jdk.compiler/com.sun.tools.javac.Main.compile(Main.java:82)
[ERROR] at jdk.internal.reflect.GeneratedMethodAccessor59.invoke(Unknown Source)
[ERROR] at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[ERROR] at java.base/java.lang.reflect.Method.invoke(Method.java:567)
[ERROR] at org.codehaus.plexus.compiler.javac.JavacCompiler.compileInProcess0(JavacCompiler.java:626)
[ERROR] at org.codehaus.plexus.compiler.javac.JavacCompiler.compileInProcessWithProperClassloader(JavacCompiler.java:607)
[ERROR] at org.codehaus.plexus.compiler.javac.JavacCompiler.compileInProcess(JavacCompiler.java:596)
[ERROR] at org.codehaus.plexus.compiler.javac.JavacCompiler.performCompile(JavacCompiler.java:178)
[ERROR] at org.apache.maven.plugin.compiler.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:1134)
[ERROR] at org.apache.maven.plugin.compiler.TestCompilerMojo.execute(TestCompilerMojo.java:180)
[ERROR] at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:137)
[ERROR] at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:210)
[ERROR] at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:156)
[ERROR] at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:148)
[ERROR] at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:117)
[ERROR] at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:81)
[ERROR] at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:56)
[ERROR] at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
[ERROR] at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:305)
[ERROR] at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:192)
[ERROR] at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:105)
[ERROR] at org.apache.maven.cli.MavenCli.execute(MavenCli.java:957)
[ERROR] at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:289)
[ERROR] at org.apache.maven.cli.MavenCli.main(MavenCli.java:193)
[ERROR] at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[ERROR] at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78)
[ERROR] at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[ERROR] at java.base/java.lang.reflect.Method.invoke(Method.java:567)
[ERROR] at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:282)
[ERROR] at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:225)
[ERROR] at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:406)
[ERROR] at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:347)


CUSTOMER SUBMITTED WORKAROUND :
Extract the method using the anonymous class to a variable so the type can be inferred. Alternatively, we can indicate the type explicitly to avoid inference at all.

FREQUENCY : always