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From: Felix Meschberger <fmeschbe@adobe.com>
To: Apache Felix Dev List <dev@felix.apache.org>
Subject: Re: Why is config admin checking for empty collections in
 Configuration values?
Thread-Topic: Why is config admin checking for empty collections in
 Configuration values?
Thread-Index: AQHPsRbeVIoyCBOi9E2agfSRSsjWx5vEtRcA
Date: Thu, 7 Aug 2014 06:48:48 +0000
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Hi David

Hmm, good question. It has always been there - ever since it was first impo=
rted into the Felix project as part of FELIX-11.

While an empty collection does not make that much sense, I think the check =
doesn't either. On the other hand: If empty collections are allowed, then i=
t must be made sure the ConfigurationHandler serializer can also read and w=
rite such empty collections.

Regards
Felix

Am 06.08.2014 um 03:35 schrieb David Jencks <david_jencks@yahoo.com.INVALID=
>:

> While writing a test I discovered that config admin doesn't like empty co=
llections or collections with empty values as configuration values.  After =
searching the 5.0 config admin spec for a while I can't find any support fo=
r these restrictions, and they are not applied to arrays.  What is the just=
ification for these checks?
>=20
> Here's the code I'm asking about (CaseInsensitiveDictionary lines 309ff)
>=20
>            if ( collection.isEmpty() )
>            {
>                throw new IllegalArgumentException( "Collection must not b=
e empty" );
>            }
>=20
>            // ensure all elements have the same type and to internal list
>            Collection internalValue =3D new ArrayList( collection.size() =
);
>            type =3D null;
>            for ( Iterator ci =3D collection.iterator(); ci.hasNext(); )
>            {
>                Object el =3D ci.next();
>                if ( el =3D=3D null )
>                {
>                    throw new IllegalArgumentException( "Collection must n=
ot contain null elements" );
>                }
>=20
>=20
> thanks
> david jencks