@Override
	protected void paintIcon( Component c, Graphics2D g ) {
		FlatTreeCollapsedIcon.setStyleColorFromTreeUI( c, g, ui -> ui.iconOpenColor );

		/*
			<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 16 16">
			  <path fill="none" stroke="#6E6E6E" d="M2,13.5 L4.11538462,8.42307692 C4.34828895,7.86410651 4.89444872,7.5 5.5,7.5 L14.75,7.5 C15.0261424,7.5 15.25,7.72385763 15.25,8 C15.25,8.06601301 15.2369281,8.13137261 15.2115385,8.19230769 L13.3846154,12.5769231 C13.151711,13.1358935 12.6055513,13.5 12,13.5 L3,13.5 C2.17157288,13.5 1.5,12.8284271 1.5,12 L1.5,4 C1.5,3.17157288 2.17157288,2.5 3,2.5 L6.29289322,2.5 C6.42550146,2.5 6.55267842,2.55267842 6.64644661,2.64644661 L8.5,4.5 L8.5,4.5 L12,4.5 C12.8284271,4.5 13.5,5.17157288 13.5,6 L13.5,6.5 L13.5,6.5"/>
			</svg>
		*/

		g.setRenderingHint( RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE );
		g.setStroke( new BasicStroke( 1, BasicStroke.CAP_BUTT, BasicStroke.JOIN_MITER ) );

		if( path == null ) {
			double arc = 1.5;
			double arc2 = 0.5;
			path = FlatUIUtils.createPath( false,
				// bottom-left of opened part
				2,13.5,
				// top-left of opened part
				FlatUIUtils.ROUNDED, 4.5,7.5, arc,
				// top-right of opened part
				FlatUIUtils.ROUNDED, 15.5,7.5, arc2,

				// bottom-right
				FlatUIUtils.ROUNDED, 13,13.5, arc,
				// bottom-left
				1.5+arc,13.5,   FlatUIUtils.QUAD_TO, 1.5,13.5,  1.5,13.5-arc,
				// top-left
				1.5,2.5+arc,    FlatUIUtils.QUAD_TO, 1.5,2.5,   1.5+arc,2.5,
				// top-mid-left
				6.5-arc2,2.5,   FlatUIUtils.QUAD_TO, 6.5,2.5,   6.5+arc2,2.5+arc2,
				// top-mid-right
				8.5,4.5,
				// top-right
				13.5-arc,4.5,   FlatUIUtils.QUAD_TO, 13.5,4.5,  13.5,4.5+arc,
				13.5,6.5 );
		}
		g.draw( path );
	}
"open" icon for {@link javax.swing.JTree} used by {@link javax.swing.tree.DefaultTreeCellRenderer}.

@uiDefault Tree.icon.openColor			Color

@author Karl Tauber
flatlaf-core/src/main/java/com/formdev/flatlaf/icons/FlatTreeOpenIcon.java