JsonInclude.Include.NON_NULL only for v3

Author: brokkoli71

src/main/java/dev/zarr/zarrjava/core/ArrayMetadata.java

@@ -1,6 +1,7 @@
 package dev.zarr.zarrjava.core;
 
 import com.fasterxml.jackson.annotation.JsonIgnore;
+import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import dev.zarr.zarrjava.ZarrException;
 import dev.zarr.zarrjava.utils.MultiArrayUtils;
@@ -16,6 +17,7 @@ public abstract class ArrayMetadata {
 
     public final long[] shape;
 
+    @JsonInclude(JsonInclude.Include.ALWAYS)
     @JsonProperty("fill_value")
     public final Object fillValue;
     @JsonIgnore

src/main/java/dev/zarr/zarrjava/v2/Node.java

@@ -20,7 +20,6 @@ static ObjectMapper makeObjectMapper() {
     ObjectMapper objectMapper = new ObjectMapper();
     objectMapper.registerModule(new Jdk8Module());
     objectMapper.registerSubtypes(CodecRegistry.getNamedTypes());
-    objectMapper.setDefaultPropertyInclusion(JsonInclude.Include.NON_NULL);
     return objectMapper;
   }