[google_maps_flutter_android] Convert PlatformPolyline.pattern to Pigeon (#7631)

Creates a structured `PlatformPatternItem` pigeon class to use in
`PlatformPolyline`.

flutter/flutter#154738

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Author: yaakovschectman

packages/google_maps_flutter/google_maps_flutter_android/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.14.7
+
+* Adds `PlatformPatternItem` pigeon class to convert `PlatformPolyline.pattern`.
+
 ## 2.14.6
 
 * Converts 'PlatformCameraUpdate' to pigeon.

packages/google_maps_flutter/google_maps_flutter_android/android/src/main/java/io/flutter/plugins/googlemaps/Convert.java

@@ -711,7 +711,7 @@ static String interpretPolylineOptions(
     sink.setWidth(polyline.getWidth());
     sink.setZIndex(polyline.getZIndex());
     sink.setPoints(pointsFromPigeon(polyline.getPoints()));
-    sink.setPattern(toPattern(polyline.getPatterns()));
+    sink.setPattern(patternFromPigeon(polyline.getPatterns()));
     return polyline.getPolylineId();
   }
 
@@ -850,32 +850,27 @@ private static List<List<LatLng>> toHoles(List<List<Messages.PlatformLatLng>> da
     return holes;
   }
 
-  private static List<PatternItem> toPattern(Object o) {
-    final List<?> data = toList(o);
-
-    if (data.isEmpty()) {
+  private static List<PatternItem> patternFromPigeon(
+      List<Messages.PlatformPatternItem> patternItems) {
+    if (patternItems.isEmpty()) {
       return null;
     }
-
-    final List<PatternItem> pattern = new ArrayList<>(data.size());
-
-    for (Object ob : data) {
-      final List<?> patternItem = toList(ob);
-      switch (toString(patternItem.get(0))) {
-        case "dot":
+    final List<PatternItem> pattern = new ArrayList<>();
+    for (Messages.PlatformPatternItem patternItem : patternItems) {
+      switch (patternItem.getType()) {
+        case DOT:
           pattern.add(new Dot());
           break;
-        case "dash":
-          pattern.add(new Dash(toFloat(patternItem.get(1))));
+        case DASH:
+          assert patternItem.getLength() != null;
+          pattern.add(new Dash(patternItem.getLength().floatValue()));
           break;
-        case "gap":
-          pattern.add(new Gap(toFloat(patternItem.get(1))));
+        case GAP:
+          assert patternItem.getLength() != null;
+          pattern.add(new Gap(patternItem.getLength().floatValue()));
           break;
-        default:
-          throw new IllegalArgumentException("Cannot interpret " + pattern + " as PatternItem");
       }
     }
-
     return pattern;
   }