add example test case

CityDoctorParent/Extensions/CityDoctorHealer/src/test/java/de/hft/stuttgart/citydoctor2/healing/bht/TestExample.java

+package de.hft.stuttgart.citydoctor2.healing.bht;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+import de.hft.stuttgart.citydoctor2.check.AbstractCheck;
+import de.hft.stuttgart.citydoctor2.check.ValidationConfiguration;
+import de.hft.stuttgart.citydoctor2.datastructure.Building;
+import de.hft.stuttgart.citydoctor2.datastructure.CityDoctorModel;
+import de.hft.stuttgart.citydoctor2.datastructure.ConcretePolygon;
+import de.hft.stuttgart.citydoctor2.datastructure.Geometry;
+import de.hft.stuttgart.citydoctor2.datastructure.Polygon;
+import de.hft.stuttgart.citydoctor2.healing.TestUtil;
+import de.hft.stuttgart.citydoctor2.parser.CityGmlParseException;
+import de.hft.stuttgart.citydoctor2.parser.InvalidGmlFileException;
+
+public class TestExample {
+	
+	public static void main(String[] args) throws CityGmlParseException, IOException, InvalidGmlFileException {
+		String path = args[0];
+		ValidationConfiguration config = ValidationConfiguration.loadStandardValidationConfig();
+		CityDoctorModel model = TestUtil.loadCityModel(path, config);
+		
+		// visitor
+		// filter duplicate polygons out
+		Set<ConcretePolygon> allBuildingPolygons = new HashSet<>();
+		for (Building b : model.getBuildings()) {
+			b.accept(new AbstractCheck() {
+				public void check(Polygon poly) {
+					allBuildingPolygons.add(poly.getOriginal());
+				}
+			});
+		}
+		
+		// for loop
+		List<Polygon> allBuildingPolygons2 = new ArrayList<>();
+		for (Building b : model.getBuildings()) {
+			for (Geometry geom : b.getGeometries()) {
+				for (Polygon p : geom.getPolygons()) {
+					allBuildingPolygons2.add(p);
+				}
+			}
+		}
+
+	}
+
+
+}