API, Core: Fix errorprone warnings (apache#9419)

* API, Core: Fix errorprone warnings

* Address comments

* Remove comment

api/src/main/java/org/apache/iceberg/util/CharSequenceSet.java

@@ -166,6 +166,7 @@ public void clear() {
     wrapperSet.clear();
   }
 
+  @SuppressWarnings("CollectionUndefinedEquality")
   @Override
   public boolean equals(Object other) {
     if (this == other) {

api/src/main/java/org/apache/iceberg/util/CharSequenceWrapper.java

@@ -44,6 +44,7 @@ public CharSequence get() {
   }
 
   @Override
+  @SuppressWarnings("UndefinedEquals")
   public boolean equals(Object other) {
     if (this == other) {
       return true;

core/src/main/java/org/apache/iceberg/DeleteFileIndex.java

@@ -161,6 +161,7 @@ private DeleteFile[] findEqPartitionDeletes(long seq, DataFile dataFile) {
     return deletes == null ? EMPTY_DELETES : deletes.filter(seq, dataFile);
   }
 
+  @SuppressWarnings("CollectionUndefinedEquality")
   private DeleteFile[] findPathDeletes(long seq, DataFile dataFile) {
     if (posDeletesByPath == null) {
       return EMPTY_DELETES;

core/src/main/java/org/apache/iceberg/avro/AvroWithPartnerByStructureVisitor.java

@@ -109,7 +109,7 @@ private static <P, T> T visitUnion(
         // types match according to the following pattern:
         // Before NULL, branch type i in the union maps to struct field i + 1.
         // After NULL, branch type i in the union maps to struct field i.
-        int structFieldIndex = (encounteredNull) ? i : i + 1;
+        int structFieldIndex = encounteredNull ? i : i + 1;
         if (types.get(i).getType() == Schema.Type.NULL) {
           visit(visitor.nullType(), types.get(i), visitor);
           encounteredNull = true;

core/src/main/java/org/apache/iceberg/deletes/SortingPositionOnlyDeleteWriter.java

@@ -116,6 +116,7 @@ private DeleteWriteResult writeFileDeletes() throws IOException {
     return new DeleteWriteResult(deleteFiles, referencedDataFiles);
   }
 
+  @SuppressWarnings("CollectionUndefinedEquality")
   private DeleteWriteResult writeDeletes(Collection<CharSequence> paths) throws IOException {
     FileWriter<PositionDelete<T>, DeleteWriteResult> writer = writers.get();