acl/src/main/java/org/springframework/security/acls/jdbc/BasicLookupStrategy.java
protected Sid createSid(boolean isPrincipal, String sid) {
		if (isPrincipal) {
			return new PrincipalSid(sid);
		}
		else {
			return new GrantedAuthoritySid(sid);
		}
	}
protected Sid createSid(boolean isPrincipal, String sid) {
		if (isPrincipal) {
			return new PrincipalSid(sid);
		}
		else {
			return new GrantedAuthoritySid(sid);
		}
	}
Creates a particular implementation of {@link Sid} depending on the arguments.

@param sid the name of the sid representing its unique identifier. In typical ACL
database schema it's located in table {@code acl_sid} table, {@code sid} column.
@param isPrincipal whether it's a user or granted authority like role
@return the instance of Sid with the {@code sidName} as an identifier