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ClassDefNoFound even though the jar that I'm dependent on is in my jar

I'm writing a LabyMod addon to create a shop bot for minecraft clients.
I've well succeeded to do so, at least in my dev-environement in eclipse. Now I wanted to publish it, and to do this, LabyMod provides a possibility to use gradle for wrapping up all stuff that is relevant to the addon in the addon jar, that can then simply be dragged into the "addons"-Folder.
However, when I do this, the plugin didn't appear in the plugin overview, and I found out that there was an error when loading the plugin (Class def not found). I use okhttp3 to send some web requests to my verification server, so I just added it in eclipse as dependent jar, but they were not included when gradle built the jar. So I wasn't very surprised with that, and looked for a possibility to add my dependencies to the jar directly.
I found out in the commments of the predefined build.gradle to simply put all files in a predefined "libs"-folder which seemed to be fine. Here's the issue: Although the jars definitely are a part of the jar, the classdefnotfound-thing still happenes. Here's what I mean.
JD-GUI says of my jar:
So, the jars definitely are there, and jd-gui can find them in the code as well, since you can click on the imports and get taken to the place where okhttp3 defined the imported class.
Here's however the error that I get, when trying to load the addon:
catching
java.lang.NoClassDefFoundError: okhttp3/OkHttpClient$Builder
at borg.locutus.grieferbot.utils.NetworkUtilities.sendGet(NetworkUtilities.java:70)
at borg.locutus.grieferbot.utils.NetworkUtilities.getPermissionLevelOfPlayer(NetworkUtilities.java:51)
at borg.locutus.grieferbot.GrieferBOTAddon.initPermissionLevel(GrieferBOTAddon.java:50)
at borg.locutus.grieferbot.GrieferBOTAddon.onEnable(GrieferBOTAddon.java:43)
at net.labymod.addon.AddonLoader.enableAddon(AddonLoader.java:349)
at net.labymod.addon.AddonLoader.enableAddons(AddonLoader.java:309)
at net.labymod.main.LabyMod.init(LabyMod.java:256)
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 net.minecraftforge.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:560)
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 com.google.common.eventbus.EventSubscriber.handleEvent(EventSubscriber.java:74)
at com.google.common.eventbus.SynchronizedEventSubscriber.handleEvent(SynchronizedEventSubscriber.java:47)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:322)
at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:304)
at com.google.common.eventbus.EventBus.post(EventBus.java:275)
at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:211)
at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:189)
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 com.google.common.eventbus.EventSubscriber.handleEvent(EventSubscriber.java:74)
at com.google.common.eventbus.SynchronizedEventSubscriber.handleEvent(SynchronizedEventSubscriber.java:47)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:322)
at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:304)
at com.google.common.eventbus.EventBus.post(EventBus.java:275)
at net.minecraftforge.fml.common.LoadController.distributeStateMessage(LoadController.java:118)
at net.minecraftforge.fml.common.Loader.initializeMods(Loader.java:737)
at net.minecraftforge.fml.client.FMLClientHandler.finishMinecraftLoading(FMLClientHandler.java:310)
at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:495)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:329)
at net.minecraft.client.main.Main.main(SourceFile:124)
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 net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
Caused by: java.lang.ClassNotFoundException: okhttp3.OkHttpClient$Builder
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 44 more
Caused by: java.lang.NullPointerException
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:182)
... 46 more
How can I make my jar find the missing dependencies?

You can't just put the dependency jars into the main jar. You need to shade the dependencies into them.

Can VisualVM profile Java 9 applications?

Hello I am trying to optimise my application, I've had JProfiler installed for the last 2 weeks but the trial period is up and I can't afford the megabucks.
I want to use VisualVM but I can't get it to work.
I installed version 1.4 from their website but when I try and open my application for profiling it does nothing. (Other available processes do open, like the intellij ide)
The error reported is as follows:
java.lang.IllegalArgumentException: Unexpected composite type for ThreadInfo
at sun.management.ThreadInfoCompositeData.validateCompositeData(ThreadInfoCompositeData.java:372)
at sun.management.ThreadInfoCompositeData.getInstance(ThreadInfoCompositeData.java:68)
at java.lang.management.ThreadInfo.<init>(ThreadInfo.java:263)
at java.lang.management.ThreadInfo.from(ThreadInfo.java:794)
Caused: java.lang.reflect.InvocationTargetException
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 sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
at sun.reflect.GeneratedMethodAccessor5.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
at com.sun.jmx.mbeanserver.DefaultMXBeanMappingFactory$CompositeBuilderViaFrom.fromCompositeData(DefaultMXBeanMappingFactory.java:1018)
Caused: java.io.InvalidObjectException: Failed to invoke from(CompositeData)
at com.sun.jmx.mbeanserver.DefaultMXBeanMappingFactory.invalidObjectException(DefaultMXBeanMappingFactory.java:1457)
at com.sun.jmx.mbeanserver.DefaultMXBeanMappingFactory$CompositeBuilderViaFrom.fromCompositeData(DefaultMXBeanMappingFactory.java:1021)
at com.sun.jmx.mbeanserver.DefaultMXBeanMappingFactory$CompositeMapping.fromNonNullOpenValue(DefaultMXBeanMappingFactory.java:919)
at com.sun.jmx.mbeanserver.DefaultMXBeanMappingFactory$NonNullMXBeanMapping.fromOpenValue(DefaultMXBeanMappingFactory.java:133)
at com.sun.jmx.mbeanserver.ConvertingMethod.fromOpenReturnValue(ConvertingMethod.java:131)
at com.sun.jmx.mbeanserver.MXBeanProxy.invoke(MXBeanProxy.java:168)
at javax.management.MBeanServerInvocationHandler.invoke(MBeanServerInvocationHandler.java:258)
Caused: java.lang.reflect.UndeclaredThrowableException
at com.sun.proxy.$Proxy14.getThreadInfo(Unknown Source)
at com.sun.tools.visualvm.jmx.impl.JmxSupport.isReadOnlyConnection(JmxSupport.java:126)
at com.sun.tools.visualvm.jmx.impl.JmxModelImpl.isTakeThreadDumpSupported(JmxModelImpl.java:369)
at com.sun.tools.visualvm.application.views.threads.ApplicationThreadsViewProvider.resolveThreads(ApplicationThreadsViewProvider.java:85)
at com.sun.tools.visualvm.application.views.threads.ApplicationThreadsViewProvider.supportsViewFor(ApplicationThreadsViewProvider.java:49)
at com.sun.tools.visualvm.application.views.threads.ApplicationThreadsViewProvider.supportsViewFor(ApplicationThreadsViewProvider.java:45)
at com.sun.tools.visualvm.core.ui.DataSourceViewsManager.getViews(DataSourceViewsManager.java:136)
at com.sun.tools.visualvm.core.ui.DataSourceWindowManager.openWindowAndAddView(DataSourceWindowManager.java:206) at com.sun.tools.visualvm.core.ui.DataSourceWindowManager.access$000(DataSourceWindowManager.java:50)
at com.sun.tools.visualvm.core.ui.DataSourceWindowManager$2.run(DataSourceWindowManager.java:117)
at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1443)
at org.netbeans.modules.openide.util.GlobalLookup.execute(GlobalLookup.java:68)
at org.openide.util.lookup.Lookups.executeWith(Lookups.java:303)
It looks like something to do with incompatible Java types? My application was compiled and run with JDK9. I've noticed VisualVM isn't even included in the java download any more. Is there a way around this?
Thanks.

Why is DDMS no longer opening?

Android DDMS was working the other day, but today (after 1.1 update) it always pops up an error message, that says to check the log file. The end of the log file is:
!ENTRY org.eclipse.osgi 4 0 2015-02-23 20:36:49.944
!MESSAGE Application error
!STACK 1
java.lang.NullPointerException
at org.eclipse.core.runtime.URIUtil.toURI(URIUtil.java:280)
at org.eclipse.e4.ui.internal.workbench.ResourceHandler.loadMostRecentModel(ResourceHandler.java:127)
at org.eclipse.e4.ui.internal.workbench.swt.E4Application.loadApplicationModel(E4Application.java:370)
at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createE4Workbench(E4Application.java:220)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:557)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:543)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at com.android.ide.eclipse.monitor.MonitorApplication.start(MonitorApplication.java:86)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:353)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:180)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:629)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:584)
at org.eclipse.equinox.launcher.Main.run(Main.java:1438)
at org.eclipse.equinox.launcher.Main.main(Main.java:1414)
The SDK seems up-to-date yet no ddms, Ubuntu 14.04. Is this a known bug or is there extra setup required for this update??

Check your processes, you likely have another instance of the monitor or ddms tool running. Pretty lame of Google not to expect that might happen and give a nice message about it.

I was facing the same issue. I tried opening DDMS the other way
Open terminal
Then go to your sdk location
then inside tools.
run ./ddms
Doing this will open ddms.

Classloading conflict with two eclipse plugins

Following situation:
At work we have an own plugin that extends some JDT features and builds some helper functions for our own framework. So far so good.
The plugin includes following class:
public class MoxLogFactory extends org.apache.commons.logging.LogFactory {
...
}
(I left out the concrete implementation because it's really comprehensive)
Now I added the WindowBuilder-Plugin to my eclipse installation. I can create new projects and classes with the wizards included. But the main feature - the editor himself - isn't working. It comes out, that the WindowBuilder tries to load the class "MoxLogFactory" from our plugin! I attached the stacktrace which comes up if I open the editor:
java.lang.ClassNotFoundException: org.dreamox.moxanos.log.MoxLogFactory
at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:501)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:421)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:412)
at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at org.apache.commons.logging.LogFactory.createFactory(LogFactory.java:1261)
at org.apache.commons.logging.LogFactory$2.run(LogFactory.java:1065)
at java.security.AccessController.doPrivileged(Native Method)
at org.apache.commons.logging.LogFactory.newFactory(LogFactory.java:1062)
at org.apache.commons.logging.LogFactory.getFactory(LogFactory.java:497)
at org.apache.commons.logging.LogFactory.getLog(LogFactory.java:704)
at org.apache.commons.digester.Digester.<init>(Digester.java:340)
at org.eclipse.wb.internal.core.model.description.helpers.ComponentDescriptionHelper.getDescription0(ComponentDescriptionHelper.java:375)
at org.eclipse.wb.internal.core.model.description.helpers.ComponentDescriptionHelper.getDescription0(ComponentDescriptionHelper.java:289)
at org.eclipse.wb.internal.core.model.description.helpers.ComponentDescriptionHelper.getDescription(ComponentDescriptionHelper.java:258)
at org.eclipse.wb.internal.core.model.JavaInfoUtils.createJavaInfo(JavaInfoUtils.java:386)
at org.eclipse.wb.internal.rcp.parser.ParseFactory.getRootContext(ParseFactory.java:184)
at org.eclipse.wb.internal.core.parser.JavaInfoParser.prepareParseContext(JavaInfoParser.java:1185)
at org.eclipse.wb.internal.core.parser.JavaInfoParser.parse(JavaInfoParser.java:244)
at org.eclipse.wb.internal.core.parser.JavaInfoParser.access$9(JavaInfoParser.java:240)
at org.eclipse.wb.internal.core.parser.JavaInfoParser$1.runObject(JavaInfoParser.java:153)
at org.eclipse.wb.internal.core.parser.JavaInfoParser$1.runObject(JavaInfoParser.java:1)
at org.eclipse.wb.internal.core.utils.execution.ExecutionUtils.runDesignTime(ExecutionUtils.java:153)
at org.eclipse.wb.internal.core.parser.JavaInfoParser.parse(JavaInfoParser.java:151)
at org.eclipse.wb.internal.core.editor.DesignPage.internal_refreshGEF(DesignPage.java:522)
at org.eclipse.wb.internal.core.editor.DesignPage.access$9(DesignPage.java:510)
at org.eclipse.wb.internal.core.editor.DesignPage$8$1.run(DesignPage.java:437)
at org.eclipse.swt.widgets.Synchronizer.syncExec(Synchronizer.java:180)
at org.eclipse.ui.internal.UISynchronizer.syncExec(UISynchronizer.java:150)
at org.eclipse.swt.widgets.Display.syncExec(Display.java:4683)
at org.eclipse.wb.internal.core.editor.DesignPage$8.run(DesignPage.java:434)
at org.eclipse.jface.operation.ModalContext.runInCurrentThread(ModalContext.java:464)
at org.eclipse.jface.operation.ModalContext.run(ModalContext.java:372)
at org.eclipse.jface.dialogs.ProgressMonitorDialog.run(ProgressMonitorDialog.java:507)
at org.eclipse.wb.internal.core.editor.DesignPage.internal_refreshGEF_withProgress(DesignPage.java:453)
at org.eclipse.wb.internal.core.editor.DesignPage.internal_refreshGEF(DesignPage.java:403)
at org.eclipse.wb.internal.core.editor.UndoManager.refreshDesignerEditor(UndoManager.java:381)
at org.eclipse.wb.internal.core.editor.UndoManager.activate(UndoManager.java:90)
at org.eclipse.wb.internal.core.editor.DesignPage.handleActiveState_True(DesignPage.java:251)
at org.eclipse.wb.internal.core.editor.DesignPage.handleActiveState(DesignPage.java:229)
at org.eclipse.wb.internal.core.editor.multi.DefaultMultiMode.showPage(DefaultMultiMode.java:125)
at org.eclipse.wb.internal.core.editor.multi.DefaultMultiMode$1.widgetSelected(DefaultMultiMode.java:63)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:240)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1077)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1062)
at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:774)
at org.eclipse.swt.custom.CTabFolder.setSelection(CTabFolder.java:2746)
at org.eclipse.swt.custom.CTabFolder.onMouse(CTabFolder.java:1433)
at org.eclipse.swt.custom.CTabFolder$1.handleEvent(CTabFolder.java:257)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4165)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3754)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:999)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:893)
at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:85)
at org.eclipse.ui.internal.Workbench$4.run(Workbench.java:579)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:534)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:124)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:352)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:624)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:579)
at org.eclipse.equinox.launcher.Main.run(Main.java:1433)
at org.eclipse.equinox.launcher.Main.main(Main.java:1409)
Our plugin doesn't export anything, so why is the WindowBuilder trying to load a class from it? Where do it gets the information to load this class? If I uninstall our plugin the WindowBuilder works fine, but I need both plugins to work efficiently.
I found, that in MoxLogFactory in one static method there is a line
System.setProperty("org.apache.commons.logging.LogFactory","org.dreamox.moxanos.log.MoxLogFactory");
I thought every plugin runs in a sandbox and so this isn't really a problem, but when I see the stacktrace, it seems, that this system property is "global in eclipse". The MoxLogFactory class is also used in our application server framework so this code is needed - the plugin uses the framework itself to work.
I don't know how to solve this problem and would appreciate any hint or idea.

Here are some options:
Remove that static initialization of the JVM level system property and replace it by a command line option only when needed
In your static initializer, test Eclipse execution context by asking the ClassLoader for org.eclipse.equinox.launcher.Main class for instance, and if so, do not set the logfactory property

System properties belong to the JVM, not to a class loader. By setting your logger as a System property, presumably so that it will be loaded automatically, you have told the entire system to use it. When the other plugin loads and attempts to initialize its logging (which appears to also use Apache Commons Logging), it reads the System property, attempts to load the class found therein, and promptly fails because it cannot see into your plugin.

eclipse rcp : class loading problem

I have plugin A which depends on Plugin B, I am trying to load a class defined in Plugin B from plugin A. And I am sure the class is in the exported packages. but I got ClassNotFoundException, did I miss any thing ?
page = (IPage) Class.forName(pageClass).newInstance();
error messages :
java.lang.ClassNotFoundException: amarsoft.dbmp.credit.web.dataobject.DOListPage
at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:513)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:429)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:417)
at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:169)
at amarsoft.rcp.base.widgets.DefaultPageRegistry.findPage(DefaultPageRegistry.java:27)
at amarsoft.rcp.base.widgets.AbstractPageControler.showPage(AbstractPageControler.java:27)
at amarsoft.rcp.base.widgets.AbstractPageControler.showPage(AbstractPageControler.java:37)
at amarsoft.dbmp.function.ui.FunctionListPage$3.linkActivated(FunctionListPage.java:261)
at org.eclipse.ui.forms.widgets.AbstractHyperlink.handleActivate(AbstractHyperlink.java:233)
at org.eclipse.ui.forms.widgets.AbstractHyperlink.handleMouseUp(AbstractHyperlink.java:327)
at org.eclipse.ui.forms.widgets.AbstractHyperlink.access$2(AbstractHyperlink.java:311)
at org.eclipse.ui.forms.widgets.AbstractHyperlink$4.handleEvent(AbstractHyperlink.java:125)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4165)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3754)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2696)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2660)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2494)
at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:674)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:667)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at amarsoft.adt.rcp.ADTApplication.start(ADTApplication.java:29)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:344)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:622)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577)
at org.eclipse.equinox.launcher.Main.run(Main.java:1410)
at org.eclipse.equinox.launcher.Main.main(Main.java:1386)

If you Require-Bundle; pluginB from pluginA, then a Class.forName(*) should have worked. Although I'll point out that using PageClass class = new PageClass(); would also work. Why are you trying to use reflection when you can just depend on that class directly?
For the common pattern where you provide a framework behaviour that other plugins should extend by providing implementations, eclipse provides the notion of Extension Points/Extensions.
Plugin A would provide an extension point. Plugin B would list an extension for that extension point, and provide an implementation class. In this case, Plugin B requires Plugin A, not the other way around.
Then Plugin A uses org.eclipse.core.runtime.IExtensionRegistry.getConfigurationElementsFor(String) to read all of the extension contributed and org.eclipse.core.runtime.IConfigurationElement.createExecutableExtension(String) to instantiate the contributed implementations (the registry takes care of making sure the class can be instantiated).