title: "WARNING: An illegal reflective access operation has occurred" with JDK 8 installed
body: <p>I just got a new computer and decided that I wanted to start dipping my toe in creating minecraft mods. Super new, have no idea what I'm doing, following a guide as I go.</p>
  <p>I've downloaded Open JDK 8, downloaded eclipse, downloaded and unzipped the forge JDK kit, imported the project as an existing gradle project, ran the genEclipseRuns gradle task, imported the launch configs of runClient and runServer, made sure I was running the right version of Minecraft in the Environments, go to run the project and I always get the following error.</p>
  <pre><code>2021-01-05 20:37:26,828 main WARN Advanced terminal features are not available in this environment
  [20:37:26] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher running: args [--gameDir, ., --launchTarget, fmluserdevserver, --fml.mcpVersion, 20201102.104115, --fml.mcVersion, 1.16.4, --fml.forgeGroup, net.minecraftforge, --fml.forgeVersion, 35.1.4]
  [20:37:26] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher 8.0.6+85+master.325de55 starting: java version 15.0.1 by Oracle Corporation
  [20:37:27] [main/DEBUG] [cp.mo.mo.LaunchServiceHandler/MODLAUNCHER]: Found launch services [minecraft,fmldevdata,fmldevclient,fmldevserver,fmluserdevserver,fmluserdevdata,testharness,fmlclient,fmluserdevclient,fmlserver]
  WARNING: An illegal reflective access operation has occurred
  WARNING: Illegal reflective access by cpw.mods.modlauncher.SecureJarHandler (file:/C:/Users/Shelby/.gradle/caches/modules-2/files-2.1/cpw.mods/modlauncher/8.0.6/70155a85837ebb17d36815ab4d12a3b464963df8/modlauncher-8.0.6.jar) to field java.util.jar.Manifest.jv
  WARNING: Please consider reporting this to the maintainers of cpw.mods.modlauncher.SecureJarHandler
  WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
  WARNING: All illegal access operations will be denied in a future release
  [20:37:27] [main/DEBUG] [cp.mo.mo.NameMappingServiceHandler/MODLAUNCHER]: Found naming services : [srgtomcp]
  [20:37:27] [main/DEBUG] [cp.mo.mo.LaunchPluginHandler/MODLAUNCHER]: Found launch plugins: [mixin,eventbus,object_holder_definalize,runtime_enum_extender,capability_inject_definalize,accesstransformer,runtimedistcleaner]
  [20:37:27] [main/DEBUG] [cp.mo.mo.TransformationServicesHandler/MODLAUNCHER]: Discovering transformation services
  ...
  </code></pre>
  <p>Further on, there is also this error:</p>
  <pre><code>...
  [20:37:28] [main/DEBUG] [ne.mi.fm.lo.ModSorter/LOADING]: Found 2 mandatory requirements
  [20:37:28] [main/DEBUG] [ne.mi.fm.lo.ModSorter/LOADING]: Found 0 mandatory mod requirements missing
  Exception in thread &quot;main&quot; [20:37:28] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]: java.lang.NoClassDefFoundError: jdk/nashorn/api/scripting/NashornScriptEngineFactory
  [20:37:28] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]:   at net.minecraftforge.coremod.CoreModEngine.loadCoreMod(CoreModEngine.java:48)
  [20:37:28] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]:   at net.minecraftforge.coremod.CoreModProvider.addCoreMod(CoreModProvider.java:12)
  [20:37:28] [main/INFO] [STDERR/]: [java.lang.ThreadGroup:uncaughtException:1048]:   at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183)
  ...
  </code></pre>
  <p>I have been pulling my hair out for the last hour trying to get this to work, I have uninstalled everything, reinstalled everything, restarted my computer, removed changed the JDK environments of the launch configs manually, anything I can think of.</p>
  <p>All other instances on google I find say that I need to not have a later installation of JDK, that I have to have JDK 8, but I have never had another version.</p>
  <p>Any help would be most appreciated.</p>