No java.lang is almost certainly a user-config error, and does not warrant a Fatal Error and stacktrace. Also the reference to bootclasspath is obsolete in a modular world.

javadoc: error - fatal error encountered: com.sun.tools.javac.util.FatalError: Fatal Error: Unable to find package java.lang in classpath or bootclasspath
javadoc: error - Please file a bug against the javadoc tool via the Java bug reporting page
(http://bugreport.java.com) after checking the Bug Database (http://bugs.java.com)
for duplicates. Include error messages and the following diagnostic in your report. Thank you.
com.sun.tools.javac.util.FatalError: Fatal Error: Unable to find package java.lang in classpath or bootclasspath
at jdk.compiler.interim/com.sun.tools.javac.comp.TypeEnter$ImportsPhase.resolveImports(TypeEnter.java:354)
at jdk.compiler.interim/com.sun.tools.javac.comp.TypeEnter$ImportsPhase.access$1700(TypeEnter.java:301)
at jdk.compiler.interim/com.sun.tools.javac.comp.TypeEnter.lambda$ensureImportsChecked$0(TypeEnter.java:168)
at jdk.compiler.interim/com.sun.tools.javac.comp.TypeEnter.finishImports(TypeEnter.java:220)
at jdk.compiler.interim/com.sun.tools.javac.comp.TypeEnter.ensureImportsChecked(TypeEnter.java:168)
at jdk.compiler.interim/com.sun.tools.javac.comp.Enter.complete(Enter.java:598)