[I] [Java] MapVector cannot be loaded via IPC [arrow-java]

[via GitHub]

vibhatha opened a new issue, #71:
URL: https://github.com/apache/arrow-java/issues/71

   ### Describe the bug, including details regarding any error messages, 
version, and platform.
   
   Referring to the stackoverflow filed issue: 
https://stackoverflow.com/questions/77878272/apache-arrow-not-all-nodes-and-buffers-were-consumed-error-when-writing-a-map
   
   The following code would yield an error;
   
   ```java
   File file = new File("test.arrow");
   
       Field keyField = new Field("id", FieldType.notNullable(new 
ArrowType.Int(64, true)),
           Collections.emptyList());
       Field valueField = new Field("value", FieldType.nullable(new 
ArrowType.Int(64, true)), Collections.emptyList());
       Field structField =
           new Field("entry", FieldType.notNullable(ArrowType.Struct.INSTANCE), 
List.of(keyField, valueField));
       Field mapIntToIntField = new Field("mapFieldIntToInt", 
FieldType.notNullable(new ArrowType.Map(false)), List.of(structField));
   
       Schema schema = new Schema(Arrays.asList(mapIntToIntField));
   
       System.out.println("Writing...");
   
       try (BufferAllocator allocator = new RootAllocator()) {
         try (
             VectorSchemaRoot vectorSchemaRoot = 
VectorSchemaRoot.create(schema, allocator);
             MapVector mapVector = (MapVector) 
vectorSchemaRoot.getVector("mapFieldIntToInt")) {
           UnionMapWriter mapWriter = mapVector.getWriter();
           mapWriter.setPosition(0);
           mapWriter.startMap();
           for (int i = 0; i < 3; i++) {
             mapWriter.startEntry();
             mapWriter.key().bigInt().writeBigInt(i);
             mapWriter.value().bigInt().writeBigInt(i * 7);
             mapWriter.endEntry();
           }
           mapWriter.endMap();
           mapWriter.setValueCount(1);
           vectorSchemaRoot.setRowCount(1);
   
           System.out.println(vectorSchemaRoot.getFieldVectors().size());
           System.out.println("vectorSchemaRoot.getVector(0): " + 
vectorSchemaRoot.getVector(0));
   
           try (
               FileOutputStream fileOutputStream = new FileOutputStream(file);
               ArrowFileWriter writer = new ArrowFileWriter(vectorSchemaRoot, 
null, fileOutputStream.getChannel())) {
             writer.start();
             writer.writeBatch();
             writer.end();
           } catch (IOException e) {
             e.printStackTrace();
           }
         }
       }
   
       System.out.println("Reading...");
   
       try(
           BufferAllocator rootAllocator = new RootAllocator();
           FileInputStream fileInputStream = new FileInputStream(file);
           ArrowFileReader reader = new 
ArrowFileReader(fileInputStream.getChannel(), rootAllocator)
       ){
         System.out.println("Record batches in file: " + 
reader.getRecordBlocks().size());
         for (ArrowBlock arrowBlock : reader.getRecordBlocks()) {
           boolean loaded = reader.loadRecordBatch(arrowBlock);
           System.out.println(loaded);
           VectorSchemaRoot vectorSchemaRootRecover = 
reader.getVectorSchemaRoot();
           System.out.print(vectorSchemaRootRecover.contentToTSVString());
         }
       } catch (IOException e) {
         e.printStackTrace();
       }
   ```
   
   Error
   
   ```bash
   Exception in thread "main" java.lang.IllegalArgumentException: not all 
nodes, buffers and variadicBufferCounts were consumed. nodes: [ArrowFieldNode 
[length=3, nullCount=0]] buffers: [ArrowBuf[24], address:123230812873128, 
capacity:1, ArrowBuf[25], address:123230812873136, capacity:24] 
variadicBufferCounts: []
        at org.apache.arrow.vector.VectorLoader.load(VectorLoader.java:98)
        at 
org.apache.arrow.vector.ipc.ArrowReader.loadRecordBatch(ArrowReader.java:214)
        at 
org.apache.arrow.vector.ipc.ArrowFileReader.loadNextBatch(ArrowFileReader.java:166)
        at 
org.apache.arrow.vector.ipc.ArrowFileReader.loadRecordBatch(ArrowFileReader.java:192)
   ```
   
   ### Component(s)
   
   Java


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