Fix crash when using AVRO CharSequence encodings and nested objects (#…

…164)

* Fix NativeDataObjectMapper
* Fix PythonDataObjectMapper

ksml-data/src/main/java/io/axual/ksml/data/mapper/NativeDataObjectMapper.java

@@ -27,6 +27,7 @@
 import io.axual.ksml.data.schema.SchemaLibrary;
 import io.axual.ksml.data.schema.StructSchema;
 import io.axual.ksml.data.type.*;
+import io.axual.ksml.data.util.MapUtil;
 import io.axual.ksml.data.value.Tuple;
 
 import java.util.ArrayList;
@@ -98,7 +99,7 @@ public DataObject toDataObject(DataType expected, Object value) {
         if (value instanceof List<?> val)
             return nativeToDataList((List<Object>) val, expected instanceof ListType expectedList ? expectedList.valueType() : DataType.UNKNOWN);
         if (value instanceof Map<?, ?> val)
-            return nativeToDataStruct((Map<String, Object>) val, expected instanceof StructType expectedStruct ? expectedStruct.schema() : null);
+            return nativeToDataStruct(MapUtil.stringKeys(val), expected instanceof StructType expectedStruct ? expectedStruct.schema() : null);
         if (value instanceof Tuple<?> val) return toDataTuple((Tuple<Object>) val);
         throw new ExecutionException("Can not convert to DataObject: " + value.getClass().getSimpleName());
     }

ksml-data/src/main/java/io/axual/ksml/data/util/MapUtil.java

@@ -0,0 +1,12 @@
+package io.axual.ksml.data.util;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class MapUtil {
+    public static Map<String, Object> stringKeys(Map<?, ?> map) {
+        final var result = new HashMap<String, Object>();
+        map.forEach((key, value) -> result.put(key != null ? key.toString() : null, value));
+        return result;
+    }
+}

ksml/src/main/java/io/axual/ksml/python/PythonDataObjectMapper.java

@@ -25,6 +25,7 @@
 import io.axual.ksml.data.mapper.NativeDataObjectMapper;
 import io.axual.ksml.data.object.*;
 import io.axual.ksml.data.type.*;
+import io.axual.ksml.data.util.MapUtil;
 import io.axual.ksml.util.ExecutionUtil;
 import org.graalvm.polyglot.Value;
 
@@ -134,7 +135,7 @@ private Object arrayToNative(DataType expected, Value object) {
     private DataObject mapToNative(DataType expected, Value object) {
         Map<?, ?> map = ExecutionUtil.tryThis(() -> object.as(Map.class));
         if (map == null) return null;
-        return nativeToDataStruct((Map<String, Object>) map, expected instanceof StructType structType ? structType.schema() : null);
+        return nativeToDataStruct(MapUtil.stringKeys(map), expected instanceof StructType structType ? structType.schema() : null);
     }
 
     @Override