Cannot build using JDK8

[davsclaus]

Caused by: java.lang.IllegalArgumentException: invalid flag: --release
at com.sun.tools.javac.api.JavacTool.processOptions (JavacTool.java:206)
at com.sun.tools.javac.api.JavacTool.getTask (JavacTool.java:156)
at com.sun.tools.javac.api.JavacTool.getTask (JavacTool.java:107)
at com.sun.tools.javac.api.JavacTool.getTask (JavacTool.java:64)
at org.codehaus.plexus.compiler.javac.JavaxToolsCompiler.compileInProcess (JavaxToolsCompiler.java:125)
at org.codehaus.plexus.compiler.javac.JavacCompiler.performCompile (JavacCompiler.java:174)
at org.apache.maven.plugin.compiler.AbstractCompilerMojo.execute (AbstractCompilerMojo.java:1134)
at org.apache.maven.plugin.compiler.CompilerMojo.execute (CompilerMojo.java:187)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke (Method.java:498)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
[ERROR]
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
[ERROR]
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR] mvn -rf :camel-k-annotations

[davsclaus]

We can build using JDK11. So either we fix this for JDK8 or we add to the building instructions that JDK11 is required for building.

[lburgazzoli]

I need to document that java 11 is required