Solve Vulnerability :: Minor Sonar issue for lastModified

public void setLastModified(final Date lastModified)
    {
        this.lastModified = lastModified;
    }
    
public Object getLastModified()
    {
        return lastModified;
    }

and sonar reporting two issues 1.Store a copy of "lastModified".

2.Return a copy of "lastModified".

how to solve this kind of issues?? can anyone help me?