[EDELIVERY-13126] improve code quality

...ava/eu/europa/ec/smp/spi/utils/xml/OffsetDateAdapter.java

...eu/europa/ec/smp/spi/utils/xml/OffsetDateTimeAdapter.java

...rc/main/java/eu/europa/ec/smp/spi/converter/DomUtils.java

...ropa/ec/smp/spi/handler/OasisSMPSubresource10Handler.java

...a/ec/edelivery/smp/auth/SMPCertificateAuthentication.java

...p/conversion/X509CertificateToCertificateROConverter.java

...n/java/eu/europa/ec/edelivery/smp/data/dao/DomainDao.java

...ava/eu/europa/ec/edelivery/smp/data/dao/ExtensionDao.java

...europa/ec/edelivery/smp/data/model/doc/DBSubresource.java

...va/eu/europa/ec/edelivery/smp/security/ResourceGuard.java

.../europa/ec/edelivery/smp/services/CRLVerifierService.java

...ropa/ec/edelivery/smp/services/SMLIntegrationService.java

...a/ec/edelivery/smp/services/mail/MailTemplateService.java

...uropa/ec/edelivery/smp/services/ui/UIPropertyService.java

...opa/ec/edelivery/smp/services/ui/UITruststoreService.java

...eu/europa/ec/edelivery/smp/services/ui/UIUserService.java

...ain/java/eu/europa/ec/edelivery/smp/sml/SmlConnector.java

.../java/eu/europa/ec/edelivery/smp/utils/PropertyUtils.java

...europa/ec/edelivery/smp/utils/StringNamedSubstitutor.java

...a/ec/edelivery/smp/data/dao/ConfigurationDAOImplTest.java