Fix Spotbug issues.

Author: phipag

powertools-kafka/src/main/java/software/amazon/lambda/powertools/kafka/serializers/AbstractKafkaDeserializer.java

@@ -16,6 +16,7 @@
 import java.io.InputStream;
 import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Base64;
 import java.util.HashMap;
@@ -263,11 +264,11 @@ private <T> T deserialize(byte[] data, Class<T> type) throws IOException {
     private <T> T deserializePrimitive(byte[] data, Class<T> type) {
         // Handle String type
         if (type == String.class) {
-            return (T) new String(data);
+            return (T) new String(data, StandardCharsets.UTF_8);
         }
 
         // Handle primitive types and their wrappers
-        String str = new String(data);
+        String str = new String(data, StandardCharsets.UTF_8);
 
         if (type == Integer.class || type == int.class) {
             return (T) Integer.valueOf(str);

powertools-kafka/src/main/java/software/amazon/lambda/powertools/kafka/serializers/KafkaJsonDeserializer.java

@@ -13,6 +13,7 @@
 package software.amazon.lambda.powertools.kafka.serializers;
 
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
 
 /**
  * Deserializer for Kafka records using JSON format.
@@ -21,7 +22,7 @@ public class KafkaJsonDeserializer extends AbstractKafkaDeserializer {
 
     @Override
     protected <T> T deserializeObject(byte[] data, Class<T> type) throws IOException {
-        String decodedStr = new String(data);
+        String decodedStr = new String(data, StandardCharsets.UTF_8);
 
         return objectMapper.readValue(decodedStr, type);
     }

powertools-kafka/src/main/java/software/amazon/lambda/powertools/kafka/serializers/LambdaDefaultDeserializer.java

@@ -15,6 +15,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.lang.reflect.Type;
+import java.nio.charset.StandardCharsets;
 
 import com.amazonaws.services.lambda.runtime.serialization.factories.JacksonFactory;
 
@@ -37,7 +38,7 @@ public <T> T fromJson(InputStream input, Type type) {
         // If the target type is String, read the input stream as a String
         if (type.equals(String.class)) {
             try {
-                return (T) new String(input.readAllBytes());
+                return (T) new String(input.readAllBytes(), StandardCharsets.UTF_8);
             } catch (IOException e) {
                 throw new RuntimeException("Failed to read input stream as String", e);
             }
@@ -56,7 +57,7 @@ public <T> T fromJson(String input, Type type) {
 
         // If the target type is InputStream, read the input stream as a String
         if (type.equals(InputStream.class)) {
-            return (T) new String(input).getBytes();
+            return (T) input.getBytes(StandardCharsets.UTF_8);
         }
 
         return (T) JacksonFactory.getInstance().getSerializer(type).fromJson(input);