static <T> void mergeFrom(InputStream in, T message, Schema<T> schema,
            boolean decodeNestedMessageAsGroup) throws IOException
    {
        final CodedInput input = new CodedInput(in, decodeNestedMessageAsGroup);
        schema.mergeFrom(input, message);
        input.checkLastTagWas(0);
    }
Merges the {@code message} from the {@link InputStream} using the given {@code schema}.
protostuff-core/src/main/java/io/protostuff/IOUtil.java