ADDITIONAL SYSTEM INFORMATION :
Bug appears present in the latest https://github.com/openjdk/jdk, and is OS-neutral

A DESCRIPTION OF THE PROBLEM :
The method `com.sun.tools.javac.code.Types.erasure` does not document any intention to deal with annotations, but in practice appears to intend to remove them: its `combineMetadata` method drops any annotations such that e.g. `@Nullable String` erases to `String`.

However, it leaves annotations specifically on (a) array types, because StructuralTypeMapping defines a visitArrayType method that preserves annotations, and (b) primitive types, because it explicitly declines to erase primitives even if they are annotated. The result is a hodge-podge of de-annotated and still-annotated types.

The version of the routine in JDK8 appears to specifically try to retain annotations, then the version in JDK9 appears to try to drop them, but misses out the case of an annotated array or annotated primitive type.

REGRESSION : Last worked in version 8

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Pass a type `@MyAnnotation int` or `@MyAnnotation int[]` or `int @MyAnnotation []` to `Types.erasure`. Contrast behaviour with `@MyAnnotation String` for example.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Either consistently keep or consistently drop annotations. Document which is intended in erasure's javadoc.
ACTUAL -
Annotations are dropped apart from array and primitive types.

---------- BEGIN SOURCE ----------
import java.lang.annotation.*;

public class Test {

  @Target({ElementType.METHOD, ElementType.FIELD, ElementType.PARAMETER, ElementType.LOCAL_VARIABLE, ElementType.TYPE_USE})
  @interface MyAnno { }

  class Inner { }

  public void annotations(@MyAnno byte[] b1, byte @MyAnno [] b2, @MyAnno String s, Class<@MyAnno String> c, @MyAnno Test.Inner ti, Class<? extends @MyAnno String> wc, Class<String>[] classes, @MyAnno byte b, @MyAnno String[] sArray, String @MyAnno [] sArray2) { }

}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Follow up the erasure visitor with one of my own dropping remaining annotations.

FREQUENCY : always