What's the purpose of SupplierJwtDecoder that lazily initialize JWTDecoder

I'm going to implement custom JwtDecoder used in OAuth2 resource server.

In the research about default JwtDecoder behaviors, I found SupplierJwtDecoder that lazily initialize JWTDecoder.

What's the advantages of deferring initialization with delegate pattern. It also seems to cause synchronizing problems.

@Override
public Jwt decode(String token) throws JwtException {
    if (this.delegate == null) {
        synchronized (this.jwtDecoderSupplier) {
            if (this.delegate == null) {
                try {
                    this.delegate = this.jwtDecoderSupplier.get();
                } catch (Exception ex) {
                    throw wrapException(ex);
                }
            }
        }
    }
    return this.delegate.decode(token);
}