Index: applications/editors/josm/plugins/graphview/src/org/openstreetmap/josm/plugins/graphview/core/property/RoadIncline.java
===================================================================
--- applications/editors/josm/plugins/graphview/src/org/openstreetmap/josm/plugins/graphview/core/property/RoadIncline.java	(revision 36270)
+++ applications/editors/josm/plugins/graphview/src/org/openstreetmap/josm/plugins/graphview/core/property/RoadIncline.java	(revision 36272)
@@ -1,4 +1,6 @@
 // License: GPL. For details, see LICENSE file.
 package org.openstreetmap.josm.plugins.graphview.core.property;
+
+import java.util.Objects;
 
 import org.openstreetmap.josm.plugins.graphview.core.access.AccessParameters;
@@ -18,5 +20,6 @@
     public <N, W, R, M> Float evaluateW(W way, boolean forward, AccessParameters accessParameters,
             DataSource<N, W, R, M> dataSource) {
-        assert way != null && accessParameters != null && dataSource != null;
+        Objects.requireNonNull(way, "way");
+        Objects.requireNonNull(dataSource, "dataSource");
 
         TagGroup tags = dataSource.getTagsW(way);