Update map key for field names for consistency

src/main/java/io/milvus/client/CollectionMapping.java

@@ -84,7 +84,7 @@ public class CollectionMapping {
         .map(f -> {
           ImmutableMap.Builder<String, Object> builder = ImmutableMap
               .<String, Object>builder()
-              .put("field", f.getName())
+              .put("name", f.getName())
               .put("type", DataType.valueOf(f.getType().getNumber()));
           String paramsInJson = getParamsInJson(f.getExtraParamsList());
           if (paramsInJson != null) {

src/test/java/io/milvus/client/MilvusGrpcClientTest.java

@@ -600,7 +600,7 @@ class MilvusClientTest {
     assertEquals(randomCollectionName, collectionMapping.getCollectionName());
 
     for (Map<String, Object> field : collectionMapping.getFields()) {
-      if (field.get("field").equals("float_vec")) {
+      if (field.get("name").equals("float_vec")) {
         JSONObject params = new JSONObject(field.get("params").toString());
         assertTrue(params.has("dim"));
       }