Misc fixes (#31624)

Author: mshima

generators/spring-boot/templates/src/main/java/_package_/_entityPackage_/service/_entityClass_QueryService.java.ejs

@@ -127,7 +127,7 @@ public class <%= serviceClassName %> extends QueryService<<%= persistClass %>> {
         if (criteria != null) {
             // This has to be called first, because the distinct method returns null
             specification = Specification.allOf(
-                Boolean.TRUE.equals(criteria.getDistinct()) ? distinct(criteria.getDistinct()) : null
+                Boolean.TRUE.equals(criteria.getDistinct()) ? distinct(criteria.getDistinct()) : Specification.unrestricted()
 <%_ for (const field of fields.filter(field => !field.transient && field.filterableField)) { _%>
                 ,
                 <%= field.fieldJavaBuildSpecification %>(criteria.get<%= field.fieldInJavaBeanMethod %>(), <%= persistClass %>_.<%= field.fieldName %>)

generators/spring-boot/templates/src/test/java/_package_/service/MailServiceIT.java.ejs

@@ -24,8 +24,10 @@ import <%= user.entityAbsoluteClass %>;
 import tech.jhipster.config.JHipsterProperties;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.ArgumentCaptor;
 import org.mockito.Captor;
+import org.mockito.junit.jupiter.MockitoExtension;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.mail.MailSendException;
 import org.springframework.mail.javamail.JavaMailSender;
@@ -53,6 +55,7 @@ import static org.mockito.Mockito.*;
 /**
  * Integration tests for {@link MailService}.
  */
+@ExtendWith(MockitoExtension.class)
 @IntegrationTest
 class MailServiceIT {