docs update

virtdata-lib-basics/src/main/java/io/nosqlbench/virtdata/library/basics/shared/conversions/from_bytebuffer/ToHexString.java

@@ -17,10 +17,16 @@ public class ToHexString implements Function<ByteBuffer,String> {
 
     private final boolean useUpperCase;
 
+    /**
+     * Convert the ByteBuffer's contents to a hex string using upper case by default.
+     */
     public ToHexString() {
         this(true);
     }
 
+    /**
+     * Convert the ByteBuffer's contents to a hex string upper or lower case.
+     */
     public ToHexString(boolean useUpperCase) {
         this.useUpperCase = useUpperCase;
     }

virtdata-lib-basics/src/main/java/io/nosqlbench/virtdata/library/basics/shared/from_long/to_bytebuffer/ToMD5ByteBuffer.java

@@ -13,7 +13,7 @@ import java.util.function.LongFunction;
 /**
  * Converts the byte image of the input long to a MD5 digest in ByteBuffer form.
  */
-@Categories(Category.conversion)
+@Categories({Category.conversion,Category.premade})
 @ThreadSafeMapper
 public class ToMD5ByteBuffer implements LongFunction<ByteBuffer> {