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/text/java/JavaAutoIndentStrategy.java
import org.eclipse.ui.texteditor.ITextEditorExtension3;
import org.eclipse.jdt.core.ToolFactory;
import org.eclipse.jdt.core.compiler.IProblem;
import org.eclipse.jdt.core.compiler.IScanner;
import org.eclipse.jdt.core.compiler.ITerminalSymbols;
import org.eclipse.jdt.core.compiler.InvalidInputException;
import org.eclipse.jdt.core.dom.AST;
import org.eclipse.jdt.core.dom.ASTNode;
import org.eclipse.jdt.core.dom.CompilationUnit;
import org.eclipse.jdt.core.dom.DoStatement;
import org.eclipse.jdt.core.dom.Expression;
import org.eclipse.jdt.core.dom.ForStatement;
import org.eclipse.jdt.core.dom.IfStatement;
import org.eclipse.jdt.core.dom.Statement;
import org.eclipse.jdt.core.dom.WhileStatement;
import org.eclipse.jdt.ui.PreferenceConstants;
import org.eclipse.jdt.internal.corext.Assert;
import org.eclipse.jdt.internal.corext.dom.NodeFinder;
import org.eclipse.jdt.internal.corext.util.CodeFormatterUtil;
import org.eclipse.jdt.internal.ui.JavaPlugin;
import org.eclipse.jdt.internal.ui.text.IJavaPartitions;
/**
 * Auto indent strategy sensitive to brackets.
 */
public class JavaAutoIndentStrategy extends DefaultAutoIndentStrategy {
		
		/**
		 * Internal line interator working on <code>IDocument</code>.
		 */
		private static final class LineIterator implements Iterator {