chore: reformat Java codebase and centralize Spotless config (#3723)

# Description of Changes

Please provide a summary of the changes, including:

- Extracted the `googleJavaFormatVersion` into a centralized Gradle
property for easier management across modules.
- Added consistent `spotless` formatting configuration to `common`,
`proprietary`, and `stirling-pdf` modules.
- Applied automatic import ordering and removed unused imports in
numerous Java files.
- Reordered and grouped imports consistently, improving overall code
readability.
- Removed excessive blank lines and standardized spacing.
- Ensured a uniform coding style throughout the codebase using Spotless
and Google Java Format with AOSP style.

---

## Checklist

### General

- [x] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [x] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md)
(if applicable)
- [x] I have performed a self-review of my own code
- [x] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md#6-testing)
for more details.

stirling-pdf/src/main/java/stirling/software/SPDF/config/AppUpdateService.java

@@ -4,7 +4,6 @@ import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Scope;
-
 import stirling.software.common.configuration.interfaces.ShowAdminInterface;
 import stirling.software.common.model.ApplicationProperties;
 

stirling-pdf/src/main/java/stirling/software/SPDF/config/CleanUrlInterceptor.java

@@ -1,16 +1,14 @@
 package stirling.software.SPDF.config;
 
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-
 import org.springframework.web.servlet.HandlerInterceptor;
 import org.springframework.web.servlet.ModelAndView;
 
-import jakarta.servlet.http.HttpServletRequest;
-import jakarta.servlet.http.HttpServletResponse;
-
 public class CleanUrlInterceptor implements HandlerInterceptor {
 
     private static final List<String> ALLOWED_PARAMS =

stirling-pdf/src/main/java/stirling/software/SPDF/config/EndpointConfiguration.java

@@ -5,12 +5,9 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
-
+import lombok.extern.slf4j.Slf4j;
 import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.stereotype.Service;
-
-import lombok.extern.slf4j.Slf4j;
-
 import stirling.software.common.model.ApplicationProperties;
 
 @Service

stirling-pdf/src/main/java/stirling/software/SPDF/config/EndpointInspector.java

@@ -5,7 +5,7 @@ import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeSet;
-
+import lombok.RequiredArgsConstructor;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.context.ApplicationContext;
@@ -17,8 +17,6 @@ import org.springframework.web.method.HandlerMethod;
 import org.springframework.web.servlet.mvc.method.RequestMappingInfo;
 import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;
 
-import lombok.RequiredArgsConstructor;
-
 @Component
 @RequiredArgsConstructor
 public class EndpointInspector implements ApplicationListener<ContextRefreshedEvent> {

stirling-pdf/src/main/java/stirling/software/SPDF/config/EndpointInterceptor.java

@@ -1,13 +1,11 @@
 package stirling.software.SPDF.config;
 
-import org.springframework.stereotype.Component;
-import org.springframework.web.servlet.HandlerInterceptor;
-
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
-
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Component;
+import org.springframework.web.servlet.HandlerInterceptor;
 
 @Component
 @Slf4j

stirling-pdf/src/main/java/stirling/software/SPDF/config/ExternalAppDepConfig.java

@@ -1,17 +1,13 @@
 package stirling.software.SPDF.config;
 
+import jakarta.annotation.PostConstruct;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
-
-import org.springframework.context.annotation.Configuration;
-
-import jakarta.annotation.PostConstruct;
-
 import lombok.extern.slf4j.Slf4j;
-
+import org.springframework.context.annotation.Configuration;
 import stirling.software.common.configuration.RuntimePathConfig;
 
 @Configuration

stirling-pdf/src/main/java/stirling/software/SPDF/config/InitialSetup.java

@@ -1,22 +1,17 @@
 package stirling.software.SPDF.config;
 
+import io.micrometer.common.util.StringUtils;
+import jakarta.annotation.PostConstruct;
 import java.io.IOException;
 import java.util.Properties;
 import java.util.UUID;
-
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
 import org.springframework.stereotype.Component;
-
-import io.micrometer.common.util.StringUtils;
-
-import jakarta.annotation.PostConstruct;
-
-import lombok.RequiredArgsConstructor;
-import lombok.extern.slf4j.Slf4j;
-
 import stirling.software.common.model.ApplicationProperties;
 import stirling.software.common.util.GeneralUtils;
 

stirling-pdf/src/main/java/stirling/software/SPDF/config/LocaleConfiguration.java

@@ -1,7 +1,7 @@
 package stirling.software.SPDF.config;
 
 import java.util.Locale;
-
+import lombok.RequiredArgsConstructor;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.web.servlet.LocaleResolver;
@@ -9,9 +9,6 @@ import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
 import org.springframework.web.servlet.i18n.LocaleChangeInterceptor;
 import org.springframework.web.servlet.i18n.SessionLocaleResolver;
-
-import lombok.RequiredArgsConstructor;
-
 import stirling.software.common.model.ApplicationProperties;
 
 @Configuration

stirling-pdf/src/main/java/stirling/software/SPDF/config/LogbackPropertyLoader.java

@@ -1,8 +1,7 @@
 package stirling.software.SPDF.config;
 
-import stirling.software.common.configuration.InstallationPathConfig;
-
 import ch.qos.logback.core.PropertyDefinerBase;
+import stirling.software.common.configuration.InstallationPathConfig;
 
 public class LogbackPropertyLoader extends PropertyDefinerBase {
     @Override

stirling-pdf/src/main/java/stirling/software/SPDF/config/MetricsConfig.java

@@ -1,11 +1,10 @@
 package stirling.software.SPDF.config;
 
-import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.Configuration;
-
 import io.micrometer.core.instrument.Meter;
 import io.micrometer.core.instrument.config.MeterFilter;
 import io.micrometer.core.instrument.config.MeterFilterReply;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
 
 @Configuration
 public class MetricsConfig {

stirling-pdf/src/main/java/stirling/software/SPDF/config/MetricsFilter.java

@@ -1,21 +1,16 @@
 package stirling.software.SPDF.config;
 
-import java.io.IOException;
-
-import org.springframework.stereotype.Component;
-import org.springframework.web.filter.OncePerRequestFilter;
-
 import io.micrometer.core.instrument.Counter;
 import io.micrometer.core.instrument.MeterRegistry;
-
 import jakarta.servlet.FilterChain;
 import jakarta.servlet.ServletException;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
 import jakarta.servlet.http.HttpSession;
-
+import java.io.IOException;
 import lombok.RequiredArgsConstructor;
-
+import org.springframework.stereotype.Component;
+import org.springframework.web.filter.OncePerRequestFilter;
 import stirling.software.common.util.RequestUriUtils;
 
 @Component

stirling-pdf/src/main/java/stirling/software/SPDF/config/OpenApiConfig.java

@@ -1,8 +1,5 @@
 package stirling.software.SPDF.config;
 
-import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.Configuration;
-
 import io.swagger.v3.oas.models.Components;
 import io.swagger.v3.oas.models.OpenAPI;
 import io.swagger.v3.oas.models.info.Contact;
@@ -10,9 +7,9 @@ import io.swagger.v3.oas.models.info.Info;
 import io.swagger.v3.oas.models.info.License;
 import io.swagger.v3.oas.models.security.SecurityRequirement;
 import io.swagger.v3.oas.models.security.SecurityScheme;
-
 import lombok.RequiredArgsConstructor;
-
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
 import stirling.software.common.model.ApplicationProperties;
 
 @Configuration

stirling-pdf/src/main/java/stirling/software/SPDF/config/StartupApplicationListener.java

@@ -1,7 +1,6 @@
 package stirling.software.SPDF.config;
 
 import java.time.LocalDateTime;
-
 import org.springframework.context.ApplicationListener;
 import org.springframework.context.event.ContextRefreshedEvent;
 import org.springframework.stereotype.Component;

stirling-pdf/src/main/java/stirling/software/SPDF/config/WebMvcConfig.java

@@ -1,12 +1,10 @@
 package stirling.software.SPDF.config;
 
+import lombok.RequiredArgsConstructor;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
 import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
-
-import lombok.RequiredArgsConstructor;
-
 import stirling.software.common.configuration.InstallationPathConfig;
 
 @Configuration