### Question:
CircularMeshGeometry extends PolygonMeshGeometry { @Override public CircularMeshGeometry derive(BaseRenderProperties renderProperties, Constraints constraints) throws ClassCastException { return new CircularMeshGeometry(createBuilder(), (PolygonMeshRenderProperties)renderProperties, constraints); } CircularMeshGeometry(Builder<?> builder, PolygonMeshRenderProperties renderProperties, Constraints constraints); @Override CircularMeshGeometry clone(); @Override Builder<? extends Position> createBuilder(); @Override CircularMeshGeometry derive(BaseRenderProperties renderProperties, Constraints constraints); Position getCenter(); double getRadius(); int getVertexCount(); double getWarpFactor();  }### Answer:
@Test public void testDerive() { CircularMeshGeometry.Builder<GeographicPosition> builder = new CircularMeshGeometry.Builder<GeographicPosition>(); builder.setDataModelId(3423L); builder.setRapidUpdate(true); builder.setNumVertices(13); builder.setRadius(.123f); builder.setWarpFactor(.0321); builder.setCenter(new GeographicPosition(LatLonAlt.createFromDegrees(34., 56.))); PolygonMeshRenderProperties renderProperties1 = new DefaultPolygonMeshRenderProperties(65763, true, true, true); TimeConstraint timeConstraint = TimeConstraint.getTimeConstraint(TimeSpan.get(10L, 20L)); Constraints constraints1 = new Constraints(timeConstraint); CircularMeshGeometry geom = new CircularMeshGeometry(builder, renderProperties1, constraints1); AbstractRenderableGeometry absGeom = geom; ColorRenderProperties renderProperties2 = renderProperties1.clone(); Constraints constraints2 = new Constraints(timeConstraint); AbstractRenderableGeometry derived = absGeom.derive(renderProperties2, constraints2); Assert.assertNotSame(geom, derived); Assert.assertEquals(geom.getDataModelId(), derived.getDataModelId()); Assert.assertEquals(geom.getRadius(), ((CircularMeshGeometry)derived).getRadius(), 0.f); Assert.assertEquals(geom.getCenter(), ((CircularMeshGeometry)derived).getCenter()); Assert.assertEquals(geom.getVertexCount(), ((CircularMeshGeometry)derived).getVertexCount()); Assert.assertEquals(geom.getPolygonVertexCount(), ((CircularMeshGeometry)derived).getPolygonVertexCount()); Assert.assertEquals(geom.getColors(), ((CircularMeshGeometry)derived).getColors()); Assert.assertEquals(geom.getNormals(), ((CircularMeshGeometry)derived).getNormals()); Assert.assertEquals(geom.getPositions(), ((CircularMeshGeometry)derived).getPositions()); Assert.assertEquals(geom.isRapidUpdate(), derived.isRapidUpdate()); Assert.assertNotSame(geom.getRenderProperties(), derived.getRenderProperties()); Assert.assertSame(renderProperties2, derived.getRenderProperties()); Assert.assertNotSame(geom.getConstraints(), derived.getConstraints()); Assert.assertSame(constraints2, derived.getConstraints()); }