code: public static Boolean getBoolean(final LdapEntry ctx, final String attribute, final Boolean nullValue) {
          val v = getString(ctx, attribute, nullValue.toString());
          if (v != null) {
              return v.equalsIgnoreCase(Boolean.TRUE.toString());
          }
          return nullValue;
      }
docs: Reads a Boolean value from the LdapEntry.
  
  @param ctx       the ldap entry
  @param attribute the attribute name
  @param nullValue the value which should be returning in case of a null value
  @return {@code true} if the attribute's value matches (case-insensitive) {@code "true"}, otherwise false