add missing imports

Author: Carsten Hollmann

spi/src/main/java/org/n52/io/geojson/GeoJSONEncoder.java

@@ -38,7 +38,9 @@
 import org.locationtech.jts.geom.MultiPolygon;
 import org.locationtech.jts.geom.Point;
 import org.locationtech.jts.geom.Polygon;
+import org.locationtech.jts.geom.impl.CoordinateArraySequence;
 import org.n52.io.crs.CRSUtils;
+import org.n52.shetland.util.JTSHelper;
 
 import com.fasterxml.jackson.databind.node.ArrayNode;
 import com.fasterxml.jackson.databind.node.JsonNodeFactory;