make marker.line.width dflt 1

... and use paper_bgcolor for marker.line.color dflt

Author: etpinard

src/traces/sunburst/attributes.js

@@ -100,8 +100,14 @@ module.exports = {
         // },
 
         line: {
-            color: pieAtts.marker.line.color,
-            width: pieAtts.marker.line.width,
+            color: extendFlat({}, pieAtts.marker.line.color, {
+                dflt: null,
+                description: [
+                    'Sets the color of the line enclosing each sector.',
+                    'Defaults to the `paper_bgcolor` value.'
+                ].join(' ')
+            }),
+            width: extendFlat({}, pieAtts.marker.line.width, {dflt: 1}),
             editType: 'calc'
         },
         editType: 'calc'

src/traces/sunburst/defaults.js

@@ -34,7 +34,7 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
     coerce('maxdepth');
 
     var lineWidth = coerce('marker.line.width');
-    if(lineWidth) coerce('marker.line.color');
+    if(lineWidth) coerce('marker.line.color', layout.paper_bgcolor);
 
     coerce('marker.colors');
 

test/image/baselines/sunburst_coffee.png

@@ -34,7 +34,8 @@
       "xanchor": "center",
       "y": 1.1,
       "yanchor": "bottom"
-    }]
+    }],
 
+    "paper_bgcolor": "#d3d3d3"
   }
 }