diff --git a/.gitignore b/.gitignore
index 2caab436965ed..828f219092375 100644
--- a/.gitignore
+++ b/.gitignore
@@ -58,3 +58,7 @@ a.out
 *.pb.h
 *.pb.cc
 *_pb2.py
+
+# Compiled executables used for docker build
+/docker/presto-cli-*-executable.jar
+/docker/presto-server-*.tar.gz
diff --git a/presto-native-execution/src/test/java/com/facebook/presto/nativeworker/ContainerQueryRunnerUtils.java b/presto-native-execution/src/test/java/com/facebook/presto/nativeworker/ContainerQueryRunnerUtils.java
index 89f9c00cbe3e6..268ec713ba51d 100644
--- a/presto-native-execution/src/test/java/com/facebook/presto/nativeworker/ContainerQueryRunnerUtils.java
+++ b/presto-native-execution/src/test/java/com/facebook/presto/nativeworker/ContainerQueryRunnerUtils.java
@@ -30,12 +30,13 @@
 import java.io.OutputStreamWriter;
 import java.io.StringReader;
 import java.nio.charset.StandardCharsets;
-import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.Properties;
 import java.util.stream.Collectors;
 
+import static com.google.common.collect.ImmutableList.toImmutableList;
+
 public class ContainerQueryRunnerUtils
 {
     private ContainerQueryRunnerUtils() {}
@@ -226,19 +227,18 @@ public static void createScriptFile(String filePath, String scriptContent)
     public static MaterializedResult toMaterializedResult(String csvData)
             throws IOException
     {
-        List<Type> columnTypes = new ArrayList<>();
-
-        // Parse CSV data using OpenCSV
-        ImmutableList<List<String>> allRows = getLists(csvData);
+        List<List<String>> allRows = parseCsvData(csvData);
 
         // Infer column types based on the maximum columns found
-        int maxColumns = allRows.stream().mapToInt(List::size).max().orElse(0);
+        int maxColumns = allRows.stream().mapToInt(row -> row.size()).max().orElse(0);
+        ImmutableList.Builder<Type> columnTypesBuilder = ImmutableList.builder();
         for (int i = 0; i < maxColumns; i++) {
             final int columnIndex = i;
-            columnTypes.add(inferType(allRows.stream()
+            columnTypesBuilder.add(inferType(allRows.stream()
                     .map(row -> columnIndex < row.size() ? row.get(columnIndex) : "")
                     .collect(Collectors.toList())));
         }
+        List<Type> columnTypes = columnTypesBuilder.build();
 
         // Convert all rows to MaterializedRow
         ImmutableList.Builder<MaterializedRow> rowsBuilder = ImmutableList.builder();
@@ -249,26 +249,17 @@ public static MaterializedResult toMaterializedResult(String csvData)
             }
             rowsBuilder.add(new MaterializedRow(5, valuesBuilder.build()));
         }
-
-        ImmutableList<MaterializedRow> materializedRows = rowsBuilder.build();
+        List<MaterializedRow> rows = rowsBuilder.build();
 
         // Create and return the MaterializedResult
-        return new MaterializedResult(materializedRows, columnTypes);
+        return new MaterializedResult(rows, columnTypes);
     }
 
-    private static ImmutableList<List<String>> getLists(String csvData)
+    private static List<List<String>> parseCsvData(String csvData)
             throws IOException
     {
         CSVReader reader = new CSVReader(new StringReader(csvData));
-        List<String[]> records = reader.readAll();
-
-        // Collect all rows as lists of strings
-        ImmutableList.Builder<List<String>> allRowsBuilder = ImmutableList.builder();
-        for (String[] record : records) {
-            allRowsBuilder.add(ImmutableList.copyOf(record));
-        }
-        ImmutableList<List<String>> allRows = allRowsBuilder.build();
-        return allRows;
+        return reader.readAll().stream().map(ImmutableList::copyOf).collect(toImmutableList());
     }
 
     private static Type inferType(List<String> values)
@@ -305,9 +296,6 @@ else if (isBoolean) {
 
     private static Object convertToType(String value, Type type)
     {
-        if (value.isEmpty()) {
-            return null;
-        }
         if (type.equals(VarcharType.VARCHAR)) {
             return value;
         }