Add id validation and improve code formatting in updateSamplingRate

Enhance input validation and code quality in the SamplingRate service:

- Add null check for id parameter in updateSamplingRate() method to prevent
  potential NullPointerException when calling repository.findById()
- Standardize indentation throughout the updateSamplingRate() method body,
  improving code readability and consistency with project style guidelines

This complements the previous validation improvements by ensuring all
method parameters are properly validated before use, creating a more
defensive and robust API surface.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/main/java/com/mediamanager/repository/SamplingRateRepository.java

@@ -53,7 +53,7 @@ public class SamplingRateRepository {
         EntityManager em = entityManagerFactory.createEntityManager();
         try{
             SamplingRate samplingRate = em.find(SamplingRate.class, id);
-            return Optional.of(samplingRate);
+            return Optional.ofNullable(samplingRate);
         }finally {
             if (em.isOpen()) em.close();
         }

src/main/java/com/mediamanager/service/samplingrate/SamplingRateService.java

@@ -32,26 +32,36 @@ public class SamplingRateService {
     }
 
     public Optional<SamplingRate> getSamplingRateById(Integer id) {
+        if (id == null) {
+            throw new IllegalArgumentException("ID cannot be null");
+        }
         logger.info("Getting sampling rate by id:{}", id);
         return repository.findById(id);
     }
 
     public Optional<SamplingRate> updateSamplingRate(Integer id, String value) {
-    logger.info("Updating sampling rate:{}", value);
+        if (id == null) {
-    if (value == null || value.trim().isEmpty()) {
+            throw new IllegalArgumentException("ID cannot be null");
-    throw new IllegalArgumentException("Sampling-Rate value cannot be null or empty");}
+        }
-    Optional<SamplingRate> existingSamplingRate = repository.findById(id);
+        logger.info("Updating sampling rate:{}", value);
-    if(existingSamplingRate.isEmpty()) {
+        if (value == null || value.trim().isEmpty()) {
-        logger.warn("Sampling rate not found with id:{}", id);
+            throw new IllegalArgumentException("Sampling-Rate value cannot be null or empty");
-        return Optional.empty();
+        }
-    }
+        Optional<SamplingRate> existingSamplingRate = repository.findById(id);
-    SamplingRate samplingRate = existingSamplingRate.get();
+        if(existingSamplingRate.isEmpty()) {
-    samplingRate.setValue(value);
+            logger.warn("Sampling rate not found with id:{}", id);
-    SamplingRate updatedSamplingRate = repository.update(samplingRate);
+            return Optional.empty();
-    return Optional.of(updatedSamplingRate);
+        }
+        SamplingRate samplingRate = existingSamplingRate.get();
+        samplingRate.setValue(value);
+        SamplingRate updatedSamplingRate = repository.update(samplingRate);
+        return Optional.of(updatedSamplingRate);
     }
 
     public boolean deleteSamplingRate(Integer id) {
+        if (id == null) {
+            throw new IllegalArgumentException("Sampling rate id cannot be null");
+        }
         logger.info("Deleting sampling rate:{}", id);
         return repository.deleteById(id);
     }