Fix NPE in JavadocThrowsCheck

[srnagar]

JavadocThrowsCheck was throwing a NPE when a method throws an exception that is declared outside the scope the method - like an instance property or static field. This issue was found in Datalake inpustream PR.

Caused by: com.puppycrawl.tools.checkstyle.api.CheckstyleException: Exception was thrown while processing C:\Repos\azure-sdk-for-java\sdk\storage\azure-storage-common\src\main\java\com\azure\storage\common\StorageInputStream.java
    at com.puppycrawl.tools.checkstyle.Checker.processFiles (Checker.java:302)
    at com.puppycrawl.tools.checkstyle.Checker.process (Checker.java:221)
    at org.apache.maven.plugins.checkstyle.exec.DefaultCheckstyleExecutor.executeCheckstyle (DefaultCheckstyleExecutor.java:201)
    at org.apache.maven.plugins.checkstyle.CheckstyleViolationCheckMojo.execute (CheckstyleViolationCheckMojo.java:545)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:208)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:154)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:146)
    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:954)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:288)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:192)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    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.NullPointerException
    at com.azure.tools.checkstyle.checks.JavadocThrowsChecks.verifyUncheckedThrowJavadoc (JavadocThrowsChecks.java:280)
    at com.azure.tools.checkstyle.checks.JavadocThrowsChecks.visitToken (JavadocThrowsChecks.java:87)
    at com.puppycrawl.tools.checkstyle.TreeWalker.notifyVisit (TreeWalker.java:335)
    at com.puppycrawl.tools.checkstyle.TreeWalker.processIter (TreeWalker.java:406)
    at com.puppycrawl.tools.checkstyle.TreeWalker.walk (TreeWalker.java:273)
    at com.puppycrawl.tools.checkstyle.TreeWalker.processFiltered (TreeWalker.java:158)
    at com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck.process (AbstractFileSetCheck.java:87)
    at com.puppycrawl.tools.checkstyle.Checker.processFile (Checker.java:328)
    at com.puppycrawl.tools.checkstyle.Checker.processFiles (Checker.java:289)
    at com.puppycrawl.tools.checkstyle.Checker.process (Checker.java:221)
    at org.apache.maven.plugins.checkstyle.exec.DefaultCheckstyleExecutor.executeCheckstyle (DefaultCheckstyleExecutor.java:201)
    at org.apache.maven.plugins.checkstyle.CheckstyleViolationCheckMojo.execute (CheckstyleViolationCheckMojo.java:545)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:208)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:154)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:146)
    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:954)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:288)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:192)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    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)

[mssfang]

LGTM!

[srnagar]

/check-enforcer override