ADDITIONAL SYSTEM INFORMATION :
Windows 10
openjdk version "11" 2018-09-25
OpenJDK Runtime Environment 18.9 (build 11+28)
OpenJDK 64-Bit Server VM 18.9 (build 11+28, mixed mode)

A DESCRIPTION OF THE PROBLEM :
javac throws an AssertionError if I compile the following code with JDK11+28.

The exception will not be thrown if I compile the class with JDK 10.0.2

REGRESSION : Last worked in version 10.0.2

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
javac JdkBug.java

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Class file
ACTUAL -
java.lang.AssertionError
        at jdk.compiler/com.sun.tools.javac.util.Assert.error(Assert.java:155)
        at jdk.compiler/com.sun.tools.javac.util.Assert.check(Assert.java:46)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr$2$1.setOverloadKind(DeferredAttr.java:172)
        at jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr.visitReference(ArgumentAttr.java:283)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMemberReference.accept(JCTree.java:2190)
        at jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr.attribArg(ArgumentAttr.java:197)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:653)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribArgs(Attr.java:751)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitApply(Attr.java:1997)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1634)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:655)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitSelect(Attr.java:3573)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCFieldAccess.accept(JCTree.java:2110)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:655)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitApply(Attr.java:2006)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1634)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:655)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr.attribSpeculative(DeferredAttr.java:498)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr.attribSpeculative(DeferredAttr.java:481)
        at jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr.lambda$processArg$0(ArgumentAttr.java:220)
        at jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr.processArg(ArgumentAttr.java:242)
        at jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr.processArg(ArgumentAttr.java:219)
        at jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr.visitApply(ArgumentAttr.java:307)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1634)
        at jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr.attribArg(ArgumentAttr.java:197)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:653)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribArgs(Attr.java:751)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitNewClass(Attr.java:2192)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCNewClass.accept(JCTree.java:1689)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:655)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitReturn(Attr.java:1866)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCReturn.accept(JCTree.java:1546)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:655)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStat(Attr.java:724)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStats(Attr.java:743)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitLambda(Attr.java:2598)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCLambda.accept(JCTree.java:1807)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:655)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr$4.complete(DeferredAttr.java:374)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr$DeferredType.check(DeferredAttr.java:335)
        at jdk.compiler/com.sun.tools.javac.comp.DeferredAttr$DeferredType.check(DeferredAttr.java:321)
        at jdk.compiler/com.sun.tools.javac.comp.Resolve$MethodResultInfo.check(Resolve.java:1060)
        at jdk.compiler/com.sun.tools.javac.comp.Resolve$4.checkArg(Resolve.java:887)
        at jdk.compiler/com.sun.tools.javac.comp.Resolve$AbstractMethodCheck.argumentsAcceptable(Resolve.java:775)
        at jdk.compiler/com.sun.tools.javac.comp.Resolve$4.argumentsAcceptable(Resolve.java:896)
        at jdk.compiler/com.sun.tools.javac.comp.Infer.instantiateMethod(Infer.java:181)
        at jdk.compiler/com.sun.tools.javac.comp.Resolve.rawInstantiate(Resolve.java:605)
        at jdk.compiler/com.sun.tools.javac.comp.Resolve.checkMethod(Resolve.java:644)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.checkMethod(Attr.java:4120)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.checkIdInternal(Attr.java:3913)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.checkMethodIdInternal(Attr.java:3814)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.checkId(Attr.java:3803)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitSelect(Attr.java:3696)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCFieldAccess.accept(JCTree.java:2110)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:655)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitApply(Attr.java:2006)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1634)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:655)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribExpr(Attr.java:695)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitVarDef(Attr.java:1174)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCVariableDecl.accept(JCTree.java:956)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:655)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStat(Attr.java:724)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStats(Attr.java:743)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:1294)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1020)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:655)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStat(Attr.java:724)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.visitMethodDef(Attr.java:1098)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:866)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:655)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStat(Attr.java:724)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:4683)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribClass(Attr.java:4574)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attribClass(Attr.java:4503)
        at jdk.compiler/com.sun.tools.javac.comp.Attr.attrib(Attr.java:4448)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.attribute(JavaCompiler.java:1341)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:973)
        at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:311)
        at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:170)
        at jdk.compiler/com.sun.tools.javac.Main.compile(Main.java:57)
        at jdk.compiler/com.sun.tools.javac.Main.main(Main.java:43)

---------- BEGIN SOURCE ----------
package com.java.bug

import java.util.Arrays;
import java.util.List;
import java.util.Optional;
import java.util.stream.Stream;

public class JdkBug {

  public static void main(String args[]) {
    List<String> commandList = Arrays.asList("command1", "command2", "command3");

    Optional<String> optionalCommandMarker = Optional.of("command2");

    Stream<CommandConfig> commandConfig = commandList.stream().map(command -> {
      return new CommandConfig(command, optionalCommandMarker.map(command::equalsIgnoreCase).orElse(false));
    });
    
    commandConfig.forEach(System.out::println);
  }

  private static class CommandConfig {
    private String command;
    private boolean isMarked;

    public CommandConfig(String command, boolean isMarked) {
      this.command = command;
      this.isMarked = isMarked;
    }

    @Override
    public String toString() {
      return "CommandConfig [command=" + command + ", isMarked=" + isMarked + "]";
    }
  }
}
---------- END SOURCE ----------

FREQUENCY : always