Adds base64 encoding for chat-API request messages

src/main/java/io/github/amithkoujalgi/ollama4j/core/models/chat/OllamaChatMessage.java

@@ -3,6 +3,10 @@ package io.github.amithkoujalgi.ollama4j.core.models.chat;
 import static io.github.amithkoujalgi.ollama4j.core.utils.Utils.getObjectMapper;
 
 import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+
+import io.github.amithkoujalgi.ollama4j.core.utils.FileToBase64Serializer;
+
 import java.io.File;
 import java.util.List;
 import lombok.AllArgsConstructor;
@@ -28,6 +32,7 @@ public class OllamaChatMessage {
     @NonNull
     private String content;
 
+    @JsonSerialize(using = FileToBase64Serializer.class)
     private List<File> images;
     
       @Override

src/main/java/io/github/amithkoujalgi/ollama4j/core/utils/FileToBase64Serializer.java

@@ -0,0 +1,31 @@
+package io.github.amithkoujalgi.ollama4j.core.utils;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.io.ObjectOutputStream;
+import java.util.Base64;
+import java.util.Collection;
+
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.databind.JsonSerializer;
+import com.fasterxml.jackson.databind.SerializerProvider;
+
+public class FileToBase64Serializer extends JsonSerializer<Collection<File>> {
+
+    @Override
+    public void serialize(Collection<File> value, JsonGenerator jsonGenerator, SerializerProvider serializers) throws IOException {
+        jsonGenerator.writeStartArray();
+        for (File file : value) {
+            jsonGenerator.writeString(Base64.getEncoder().encodeToString(serialize(file)));
+        }
+        jsonGenerator.writeEndArray();
+    }
+
+    public static byte[] serialize(Object obj) throws IOException {
+        ByteArrayOutputStream out = new ByteArrayOutputStream();
+        ObjectOutputStream os = new ObjectOutputStream(out);
+        os.writeObject(obj);
+        return out.toByteArray();
+    }
+}