For convenience added convertToUperCase on LdapAuthenticationProviderConfigurer

[domi-87]

Since LdapAuthenticationProviderConfigurer currently does not offer the possibility to pass the flag convertToUpperCase to the DefaultLdapAuthoritiesPopulator, I have extended this feature on the LdapAuthenticationProviderConfigurer accordingly. Previously, if you only wanted to set convertToUpperCase to 'false', you had to initialize the DefaultLdapAuthoritiesPopulator yourself and set all values accordingly.

Until now:

protected void configure(AuthenticationManagerBuilder auth) throws Exception {
  final var ldapAuth = auth.ldapAuthentication();

  final var authoritiesPopulator = new DefaultLdapAuthoritiesPopulator(contextSource, groupSearchBase);
  authoritiesPopulator.setGroupRoleAttribute(groupRoleAttribute);
  authoritiesPopulator.setGroupSearchFilter(groupSearchFilter);
  authoritiesPopulator.setSearchSubtree(groupSearchSubtree);
  authoritiesPopulator.setRolePrefix(rolePrefix);
  authoritiesPopulator.setConvertToUpperCase(false);
  ldapAuth.ldapAuthoritiesPopulator(authoritiesPopulator);
}

New:

protected void configure(AuthenticationManagerBuilder auth) throws Exception {
  final var ldapAuth = auth.ldapAuthentication();
  ldapAuth.convertToUpperCase(false);
}

[eleftherias]

Thanks for the suggestion @domi-87.

Using the AuthenticationManagerBuilder is no longer the preferred way of configuring LDAP authentication, which is why we aren't looking to add any additional functionality to it.

Currently the preferred way to set convertToUpperCase is to do something like this:

@Bean
LdapAuthenticationProvider authenticationProvider(LdapAuthenticator authenticator) {
	DefaultLdapAuthoritiesPopulator authoritiesPopulator = new DefaultLdapAuthoritiesPopulator(
			this.contextSource, this.groupSearchBase);
	authoritiesPopulator.setConvertToUpperCase(false);
	LdapAuthenticationProvider provider = new LdapAuthenticationProvider(authenticator, authoritiesPopulator);
	provider.setUserDetailsContextMapper(new PersonContextMapper());
	return provider;
}

We are planning to introduce a LdapAuthenticationManagerFactoryBean, which will make it easier to create an AuthenticationManager that can perform LDAP authentication.
You can track the progress in gh-10138.

For those reasons I am going to close this PR, but I will keep your suggestion in mind while working on the LdapAuthenticationManagerFactoryBean.