address static analysis findings

serde-bson/src/main/java/io/micronaut/serde/bson/BsonReaderDecoder.java

@@ -397,10 +397,11 @@ private byte[] copyValueToDocument() {
     @Override
     public Decoder decodeBuffer() throws IOException {
         byte[] documentBytes = decodeCustom(p -> ((BsonReaderDecoder) p).copyValueToDocument());
-        BsonReaderDecoder topDecoder = new BsonReaderDecoder(new BsonBinaryReader(ByteBuffer.wrap(documentBytes)));
-        Decoder objectDecoder = topDecoder.decodeObject();
-        objectDecoder.decodeKey(); // skip key
-        return objectDecoder;
+        try (BsonReaderDecoder topDecoder = new BsonReaderDecoder(new BsonBinaryReader(ByteBuffer.wrap(documentBytes)))) {
+            Decoder objectDecoder = topDecoder.decodeObject();
+            objectDecoder.decodeKey(); // skip key
+            return objectDecoder;
+        }
     }
 
     private static void transfer(BsonReader src, BsonWriter dest, BsonType type) {

serde-support/src/main/java/io/micronaut/serde/support/DefaultSerdeIntrospections.java

@@ -83,7 +83,7 @@ public <T> BeanIntrospection<T> getSerializableIntrospection(Argument<T> type) {
                 if (candidates.size() == 1) {
                     result = (BeanIntrospection<T>) candidates.iterator().next();
                 } else {
-                    result = (BeanIntrospection<T>) OrderUtil.sort(candidates.stream()).findFirst().get();
+                    result = (BeanIntrospection<T>) OrderUtil.sort(candidates.stream()).findFirst().orElse(null);
                 }
             }
         }

serde-support/src/main/java/io/micronaut/serde/support/deserializers/SpecificObjectDeserializer.java

@@ -33,6 +33,7 @@
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.Map;
+import java.util.NoSuchElementException;
 
 /**
  * Implementation for deserialization of objects that uses introspection metadata.
@@ -790,12 +791,15 @@ public boolean hasNext() {
                 }
 
                 @Override
-                public SpecificObjectDeserializer.TokenBuffer next() {
+                public SpecificObjectDeserializer.TokenBuffer next() throws NoSuchElementException {
                     if (thisBuffer == null) {
                         thisBuffer = SpecificObjectDeserializer.TokenBuffer.this;
                     } else {
                         thisBuffer = thisBuffer.next;
                     }
+                    if (thisBuffer == null) {
+                        throw new NoSuchElementException();
+                    }
                     return thisBuffer;
                 }
             };
@@ -835,12 +839,16 @@ public boolean hasNext() {
                 }
 
                 @Override
-                public SpecificObjectDeserializer.PropertyBuffer next() {
+                public SpecificObjectDeserializer.PropertyBuffer next() throws NoSuchElementException {
                     if (thisBuffer == null) {
                         thisBuffer = SpecificObjectDeserializer.PropertyBuffer.this;
                     } else {
                         thisBuffer = thisBuffer.next;
                     }
+
+                    if (thisBuffer == null) {
+                        throw new NoSuchElementException();
+                    }
                     return thisBuffer;
                 }
             };

serde-support/src/main/java/io/micronaut/serde/support/serializers/ObjectSerializer.java

@@ -200,9 +200,10 @@ public void serialize(Encoder encoder, EncoderContext context, Argument<?> type,
                 throws IOException {
             if (value == null) {
                 encoder.encodeNull();
+            } else {
+                Argument<Object> arg = Argument.of((Class) value.getClass());
+                getSerializer(context, value).serialize(encoder, context, arg, value);
             }
-            Argument<Object> arg = Argument.of((Class) value.getClass());
-            getSerializer(context, value).serialize(encoder, context, arg, value);
         }
 
         @Override

serde-support/src/main/java/io/micronaut/serde/support/serializers/RuntimeValueIterableSerializer.java

@@ -42,7 +42,7 @@ public void serialize(Encoder encoder, EncoderContext context, Argument<? extend
                 encoder.encodeNull();
                 continue;
             }
-            if (lastValueClass != t.getClass()) {
+            if (lastValueClass != t.getClass() || componentSerializer == null) {
                 generic = (Argument<T>) Argument.of(t.getClass());
                 componentSerializer = context.findSerializer(generic).createSpecific(context, generic);
                 lastValueClass = t.getClass();