storm-apt/impl/src/main/java/com/turbomanage/storm/apt/StormEnvironment.java
void writeIndex(Filer filer) {
		StandardLocation location = StandardLocation.SOURCE_OUTPUT;
		FileObject indexFile;
		try {
			indexFile = filer.createResource(location, "com.turbomanage.storm",
					ENV_FILE);
			OutputStream fos = indexFile.openOutputStream();
			PrintWriter out = new PrintWriter(fos);
			// Dump converters
			out.println(BEGIN_CONVERTERS);
			for (ConverterModel converter : converters) {
				converter.writeToIndex(out);
			}
			out.println(END_CONVERTERS);
			// Dump databases
			for (DatabaseModel dbModel : dbModels.values()) {
				dbModel.writeToIndex(out);
			}
			out.close();
		} catch (IOException e) {
			throw new RuntimeException(e);
		}
	}
void writeIndex(Filer filer) {
		StandardLocation location = StandardLocation.SOURCE_OUTPUT;
		FileObject indexFile;
		try {
			indexFile = filer.createResource(location, "com.turbomanage.storm",
					ENV_FILE);
			OutputStream fos = indexFile.openOutputStream();
			PrintWriter out = new PrintWriter(fos);
			// Dump converters
			out.println(BEGIN_CONVERTERS);
			for (ConverterModel converter : converters) {
				converter.writeToIndex(out);
			}
			out.println(END_CONVERTERS);
			// Dump databases
			for (DatabaseModel dbModel : dbModels.values()) {
				dbModel.writeToIndex(out);
			}
			out.close();
		} catch (IOException e) {
			throw new RuntimeException(e);
		}
	}
Write the current model state to a file in support of incremental
compilation.

@see StormEnvironment#readIndex(Filer)

@param Filer
used by the annotation processor