Prefer static inner classes

Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com>

org.eclipse.jgit.ui/src/org/eclipse/jgit/awtui/CommitGraphPane.java

 		}
 	}
 
-	class NameCellRender extends DefaultTableCellRenderer {
+	static class NameCellRender extends DefaultTableCellRenderer {
 		private static final long serialVersionUID = 1L;
 
 		public Component getTableCellRendererComponent(final JTable table,
 		}
 	}
 
-	class DateCellRender extends DefaultTableCellRenderer {
+	static class DateCellRender extends DefaultTableCellRenderer {
 		private static final long serialVersionUID = 1L;
 
 		private final DateFormat fmt = new SimpleDateFormat(
 		}
 	}
 
-	class GraphCellRender extends DefaultTableCellRenderer {
+	static class GraphCellRender extends DefaultTableCellRenderer {
 		private static final long serialVersionUID = 1L;
 
 		private final AWTPlotRenderer renderer = new AWTPlotRenderer(this);