Inline Files.write() in GenApiConfigAction (#175)

Files.write is deprecated and scheduled for removal. Changing this to use Files.asCharSink().write() is the same implementation, but is not deprecated.

Author: nick-someone

endpoints-framework-tools/src/main/java/com/google/api/server/spi/tools/GenApiConfigAction.java

@@ -104,7 +104,7 @@ public Iterable<String> genApiConfig(
         String apiConfigFileName = entry.getKey();
         String apiConfigFileContent = entry.getValue();
         String apiConfigFilePath = outputDir + "/" + apiConfigFileName;
-        Files.write(apiConfigFileContent, new File(apiConfigFilePath), UTF_8);
+        Files.asCharSink(new File(apiConfigFilePath), UTF_8).write(apiConfigFileContent);
         System.out.println("API configuration written to " + apiConfigFilePath);
       }
     }