GH-3215: Sort the list of org.apache.parquet.format.Encoding (#3413)

* GH-3215: Sort the list of org.apache.parquet.format.Encoding created by org.apache.parquet.format.converter.ParquetMetadataConverter::toFormatEncodings

* GH-3215: Reformat test case to address format violations failures.

---------

Co-authored-by: Peter Franzen <peter@myire.org>
Co-authored-by: Mikael Brännström <mikael.brannstrom@ngm.se>

Author: 3 people

parquet-hadoop/src/main/java/org/apache/parquet/format/converter/ParquetMetadataConverter.java

@@ -703,11 +703,13 @@ private void addRowGroup(
     rowGroups.add(rowGroup);
   }
 
-  private List<Encoding> toFormatEncodings(Set<org.apache.parquet.column.Encoding> encodings) {
+  // Visible for testing
+  List<Encoding> toFormatEncodings(Set<org.apache.parquet.column.Encoding> encodings) {
     List<Encoding> converted = new ArrayList<Encoding>(encodings.size());
     for (org.apache.parquet.column.Encoding encoding : encodings) {
       converted.add(getEncoding(encoding));
     }
+    Collections.sort(converted);
     return converted;
   }
 

parquet-hadoop/src/test/java/org/apache/parquet/format/converter/TestParquetMetadataConverter.java

@@ -759,6 +759,22 @@ public void testEncodingsCache() {
     assertEquals("java.util.Collections$UnmodifiableSet", res3.getClass().getName());
   }
 
+  @Test
+  public void testEncodingsOrder() {
+    ParquetMetadataConverter parquetMetadataConverter = new ParquetMetadataConverter();
+
+    Set<org.apache.parquet.column.Encoding> columnEncodings =
+        new HashSet<>(Arrays.asList(org.apache.parquet.column.Encoding.values()));
+
+    // Assert that the encodings are returned in ascending ordinal order
+    List<org.apache.parquet.format.Encoding> formatEncodings =
+        parquetMetadataConverter.toFormatEncodings(columnEncodings);
+    for (int i = 1; i < formatEncodings.size(); i++) {
+      assertTrue(formatEncodings.get(i - 1).ordinal()
+          < formatEncodings.get(i).ordinal());
+    }
+  }
+
   @Test
   public void testBinaryStatsV1() {
     testBinaryStats(StatsHelper.V1);