src/jdk.jextract/share/classes/com/sun/tools/jextract/Context.java

*** 53,58 ****
--- 53,62 ----
      }
  
      public static Path getBuiltinHeadersDir() {
          return Paths.get(System.getProperty("java.home"), "conf", "jextract");
      }
+ 
+     public static Path getBuiltinHeaderFile() {
+         return getBuiltinHeadersDir().resolve("builtin$.h");
+     }
  }