[jnigen] Close #1354 (#1553)

Author: HosseinYousefi

pkgs/jnigen/CHANGELOG.md

@@ -14,6 +14,7 @@
 - Fixed an issue where inheriting a generic class could generate incorrect code.
 - No longer generating constructors for abstract classes.
 - No longer generating `protected` elements.
+- Fixed an issue where synthetic methods caused code generation to fail.
 
 ## 0.11.0
 

pkgs/jnigen/lib/src/elements/elements.dart

@@ -531,7 +531,11 @@ class Param implements Element<Param> {
 
   final List<Annotation> annotations;
   final JavaDocComment? javadoc;
+
+  // Synthetic methods might not have parameter names.
+  @JsonKey(defaultValue: 'synthetic')
   final String name;
+
   final TypeUsage type;
 
   /// Populated by [Renamer].