Extend convert-null parameter to all data types

• Type: Feature Request
• Status: Under Review
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: None
• Fix Version/s: None
• Component/s: Core Infrastructure > Service Builder
• Labels: None

Background
Service builder automatically converts null values to empty values ("", 0, etc).
With LEP-1353, a new convert-null parameter was introduced to allow null strings.

Issue
This parameter was only applied to String data types. The rest of data types do not allow null values as they are auto-converted to the data type's default value.

null conversion code:
service.xml: https://github.com/liferay/liferay-portal/blob/master/portal-impl/src/com/liferay/portal/service.xml#L156
hibernate: https://github.com/liferay/liferay-portal/blob/master/portal-impl/src/META-INF/portal-hbm.xml#L177
data mapping: https://github.com/liferay/liferay-portal/blob/master/portal-impl/src/com/liferay/portal/dao/orm/hibernate/IntegerType.java#L90-L122

Contributed solution
for Liferay 6.0 in LPS-14863

Request
Extend the convert-null parameter to the rest of data types