Attempting to build with jdk7 on master gives misleading error

[INFO] --- sortpom-maven-plugin:2.5.0:sort (sort-pom) @ accumulo-project ---
[WARN] Error injecting: sortpom.SortMojo
java.lang.TypeNotPresentException: Type sortpom.SortMojo not present
	at org.eclipse.sisu.space.URLClassSpace.loadClass(URLClassSpace.java:115)
	at org.eclipse.sisu.space.NamedClass.load(NamedClass.java:46)
	at org.eclipse.sisu.space.AbstractDeferredClass.get(AbstractDeferredClass.java:48)
	at com.google.inject.internal.ProviderInternalFactory.provision(ProviderInternalFactory.java:86)
	at com.google.inject.internal.InternalFactoryToInitializableAdapter.provision(InternalFactoryToInitializableAdapter.java:55)
	at com.google.inject.internal.ProviderInternalFactory$1.call(ProviderInternalFactory.java:70)
	at com.google.inject.internal.ProvisionListenerStackCallback$Provision.provision(ProvisionListenerStackCallback.java:100)
	at org.eclipse.sisu.plexus.PlexusLifecycleManager.onProvision(PlexusLifecycleManager.java:133)
	at com.google.inject.internal.ProvisionListenerStackCallback$Provision.provision(ProvisionListenerStackCallback.java:109)
	at com.google.inject.internal.ProvisionListenerStackCallback.provision(ProvisionListenerStackCallback.java:55)
	at com.google.inject.internal.ProviderInternalFactory.circularGet(ProviderInternalFactory.java:68)
	at com.google.inject.internal.InternalFactoryToInitializableAdapter.get(InternalFactoryToInitializableAdapter.java:47)
	at com.google.inject.internal.InjectorImpl$2$1.call(InjectorImpl.java:997)
	at com.google.inject.internal.InjectorImpl.callInContext(InjectorImpl.java:1047)
	at com.google.inject.internal.InjectorImpl$2.get(InjectorImpl.java:993)
	at com.google.inject.Scopes$1$1.get(Scopes.java:59)
	at org.eclipse.sisu.inject.LazyBeanEntry.getValue(LazyBeanEntry.java:82)
	at org.eclipse.sisu.plexus.LazyPlexusBean.getValue(LazyPlexusBean.java:51)
	at org.codehaus.plexus.DefaultPlexusContainer.lookup(DefaultPlexusContainer.java:260)
	at org.codehaus.plexus.DefaultPlexusContainer.lookup(DefaultPlexusContainer.java:252)
	at org.apache.maven.plugin.internal.DefaultMavenPluginManager.getConfiguredMojo(DefaultMavenPluginManager.java:462)
	at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:119)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:208)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:116)
	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
	at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
	at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:120)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:347)
	at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:154)
	at org.apache.maven.cli.MavenCli.execute(MavenCli.java:582)
	at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:214)
	at org.apache.maven.cli.MavenCli.main(MavenCli.java:158)
	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.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
	at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
	at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
Caused by: java.lang.UnsupportedClassVersionError: sortpom/SortMojo : Unsupported major.minor version 52.0
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
	at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
	at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
	at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClassFromSelf(ClassRealm.java:389)
	at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:42)
	at org.codehaus.plexus.classworlds.realm.ClassRealm.unsynchronizedLoadClass(ClassRealm.java:259)
	at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:235)
	at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:227)
	at org.eclipse.sisu.space.URLClassSpace.loadClass(URLClassSpace.java:107)
	... 41 more