public Optional<Extern> getWasmExtern(final String wasiFuncName) {
        return linker.get(store, "", wasiFuncName);
    }
get the WASI function.

@param wasiFuncName the WASI function name
@return the WASI function
shenyu-plugin/shenyu-plugin-wasm-api/src/main/java/org/apache/shenyu/plugin/wasm/api/loader/WasmLoader.java