Bug 40772 [plan item] Smart tab on empty lines
When having the caret on an empty line, pressing tab cleans up the line and sets the caret it the right indentation column.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitEditor.java
import java.lang.reflect.InvocationTargetException;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Stack;
import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IWorkspace;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.Preferences;
import org.eclipse.swt.custom.VerifyKeyListener;
import org.eclipse.swt.events.VerifyEvent;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.jface.action.Action;
import org.eclipse.jface.action.IMenuManager;
import org.eclipse.jface.dialogs.ErrorDialog;
import org.eclipse.jface.dialogs.IMessageProvider;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.jface.dialogs.ProgressMonitorDialog;
import org.eclipse.jface.preference.IPreferenceStore;
import org.eclipse.jface.util.PropertyChangeEvent;
import org.eclipse.jface.viewers.ISelectionProvider;
import org.eclipse.jface.window.Window;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.DocumentCommand;