fix(java): avoid double JNI env borrow for metadata

Author: majin1102

java/lance-jni/src/blocking_dataset.rs

@@ -2387,6 +2387,8 @@ fn inner_list_tags<'local>(
         } else {
             JObject::null()
         };
+        let java_metadata =
+            crate::traits::JLance(tag_contents.metadata.as_deref()).into_java(env)?;
         let java_tag = env.new_object(
             "org/lance/Tag",
             "(Ljava/lang/String;Ljava/lang/String;JILjava/lang/String;)V",
@@ -2395,9 +2397,7 @@ fn inner_list_tags<'local>(
                 JValue::Object(&branch_name),
                 JValue::Long(tag_contents.version as i64),
                 JValue::Int(tag_contents.manifest_size as i32),
-                JValue::Object(
-                    &crate::traits::JLance(tag_contents.metadata.as_deref()).into_java(env)?,
-                ),
+                JValue::Object(&java_metadata),
             ],
         )?;
         env.call_method(
@@ -2558,6 +2558,7 @@ fn inner_list_branches<'local>(
         } else {
             JObject::null()
         };
+        let java_metadata = crate::traits::JLance(contents.metadata.as_deref()).into_java(env)?;
         let jbranch = env.new_object(
             "org/lance/Branch",
             "(Ljava/lang/String;Ljava/lang/String;JJILjava/lang/String;)V",
@@ -2567,9 +2568,7 @@ fn inner_list_branches<'local>(
                 JValue::Long(contents.parent_version as i64),
                 JValue::Long(contents.create_at as i64),
                 JValue::Int(contents.manifest_size as i32),
-                JValue::Object(
-                    &crate::traits::JLance(contents.metadata.as_deref()).into_java(env)?,
-                ),
+                JValue::Object(&java_metadata),
             ],
         )?;
         env.call_method(