CodeGen fails when case class fields are reserved java keywords

It is possible to define a case class with reserve field names using back-ticks.

case class Foo(a: String, `if`: Int)
val t = TypedDataset.create(Seq(Foo("a",2), Foo("b",2)))

Fails with the following error:

17/06/01 00:45:54 ERROR CodeGenerator: failed to compile: org.codehaus.commons.compiler.CompileException: File 'generated.java', Line 49, Column 44: Unexpected selector 'if' after "."
/* 001 */ public java.lang.Object generate(Object[] references) {
/* 002 */   return new SpecificUnsafeProjection(references);
/* 003 */ }
/* 004 */
/* 005 */ class SpecificUnsafeProjection extends org.apache.spark.sql.catalyst.expressions.UnsafeProjection {
/* 006 */
/* 007 */   private Object[] references;
/* 008 */   private UnsafeRow result;
/* 009 */   private org.apache.spark.sql.catalyst.expressions.codegen.BufferHolder holder;
/* 010 */   private org.apache.spark.sql.catalyst.expressions.codegen.UnsafeRowWriter rowWriter;
/* 011 */
/* 012 */
/* 013 */   public SpecificUnsafeProjection(Object[] references) {
/* 014 */     this.references = references;
/* 015 */     result = new UnsafeRow(2);
/* 016 */     this.holder = new org.apache.spark.sql.catalyst.expressions.codegen.BufferHolder(result, 32);
/* 017 */     this.rowWriter = new org.apache.spark.sql.catalyst.expressions.codegen.UnsafeRowWriter(holder, 2);
/* 018 */   }
/* 019 */
/* 020 */   // Scala.Function1 need this
/* 021 */   public java.lang.Object apply(java.lang.Object row) {
/* 022 */     return apply((InternalRow) row);
/* 023 */   }
/* 024 */
/* 025 */   public UnsafeRow apply(InternalRow i) {
/* 026 */     holder.reset();
/* 027 */
/* 028 */     rowWriter.zeroOutNullBytes();
/* 029 */
/* 030 */
/* 031 */     $line48.$read$$iw$$iw$$iw$$iw$$iw$$iw$Foo value2 = ($line48.$read$$iw$$iw$$iw$$iw$$iw$$iw$Foo)i.get(0, null);
/* 032 */
/* 033 */     boolean isNull1 = false;
/* 034 */     final java.lang.String value1 = isNull1 ? null : (java.lang.String) value2.a();
/* 035 */     isNull1 = value1 == null;
/* 036 */     boolean isNull = isNull1;
/* 037 */     final UTF8String value = isNull ? null : org.apache.spark.unsafe.types.UTF8String.fromString(value1);
/* 038 */     isNull = value == null;
/* 039 */     if (isNull) {
/* 040 */       rowWriter.setNullAt(0);
/* 041 */     } else {
/* 042 */       rowWriter.write(0, value);
/* 043 */     }
/* 044 */
/* 045 */
/* 046 */     $line48.$read$$iw$$iw$$iw$$iw$$iw$$iw$Foo value4 = ($line48.$read$$iw$$iw$$iw$$iw$$iw$$iw$Foo)i.get(0, null);
/* 047 */
/* 048 */     boolean isNull3 = false;
/* 049 */     final int value3 = isNull3 ? -1 : value4.if();
/* 050 */     if (isNull3) {
/* 051 */       rowWriter.setNullAt(1);
/* 052 */     } else {
/* 053 */       rowWriter.write(1, value3);
/* 054 */     }
/* 055 */     result.setTotalSize(holder.totalSize());
/* 056 */     return result;
/* 057 */   }
/* 058 */ }

Start by reproducing the Scala case class example and inspect the CodeGen path that produces generated.java. Focus on how accessors are emitted for fields named with reserved Java keywords. Done means the example compiles and TypedDataset.create succeeds without the generated.java selector error.