HONEYCOMB-270 Add isPresent() to Readers/Customizers

So that they can influence whether empty data is to be considered as present

+ Move registries implementations from util to impl
+ Introduce DelegatingReader trait
+ Extend GenericReader where possible to reduce duplication

Change-Id: I5a416acd0c4eab1fbc30fcbe585719991dbe9215
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>

1 files changed, 3 insertions, 6 deletions

diff --git a/infra/translate-utils/src/main/java/io/fd/honeycomb/translate/util/read/AbstractGenericReader.java b/infra/translate-utils/src/main/java/io/fd/honeycomb/translate/util/read/AbstractGenericReader.java
index 40c78b3c9..b19b72ecf 100644
--- a/infra/translate-utils/src/main/java/io/fd/honeycomb/translate/util/read/AbstractGenericReader.java
+++ b/infra/translate-utils/src/main/java/io/fd/honeycomb/translate/util/read/AbstractGenericReader.java
@@ -56,18 +56,15 @@ public abstract class AbstractGenericReader<D extends DataObject, B extends Buil
                                       @Nonnull final ReadContext ctx) throws ReadFailedException {
         LOG.debug("{}: Reading current: {}", this, id);
         final B builder = getBuilder(id);
-        // The empty value could be cached, but no caching is safer since we call overridden getBuilder each time
-        // and the build could produce something different (even if it shouldn't)
-        final D emptyValue = builder.build();
 
         LOG.trace("{}: Reading current attributes", this);
         readCurrentAttributes(id, builder, ctx);
 
         // Need to check whether anything was filled in to determine if data is present or not.
         final D built = builder.build();
-        final Optional<D> read = built.equals(emptyValue)
-            ? Optional.absent()
-            : Optional.of(built);
+        final Optional<D> read = isPresent(id, built, ctx)
+            ? Optional.of(built)
+            : Optional.absent();
 
         LOG.debug("{}: Current node read successfully. Result: {}", this, read);
         return read;