Add the ability to specify a Case Prefix Expression

The idea behind this jira is allow the customize not only the sequence name / prefix of the cases but also the expression for generating the caseId using MVEL templates.

1. It will provide some functions like:
   1. LPAD (left padding)
   2. RPAD (right padding)
   3. TRUNCATE( truncante by left)
   4. UPPER

1. It will provide some implicit variables like:
   1. CASE_PREFIX_ID
   2. DEPLOYMENT_ID
   3. CASE_DEFINITION_ID
   4. Case Variables. They could be use for replacement expansion.
2. global variable will be provided to modify the standard way of generating case ID

   System.getProperty("org.kie.jbpm.cases.id.generator.default_prefix", "CASE");
   

For instance. At present this works the default expressions

prefix := "CASE"

this generates the next sequence:

CASE-0000000001
CASE-0000000002
CASE-0000000003
CASE-0000000004

another example for the same processId

case variable =>  type = "type1"
prefix = "HR-@{UPPER(type})"

this would generate (sequence name /prefix would be HR-TYPE1)

HR-TYPE1-0000000001
HR-TYPE1-0000000002
HR-TYPE1-0000000003

providing a different case variable i.e (type = 3type) would generate:

HR-3TYPE-0000000001
HR-3TYPE-0000000002
HR-3TYPE-0000000003

with sequence name / prefix HR-3TYPE

If the case variable IS_PREFIX_SEQUENCE is set to false (default value is true) it won't create any sequence and the caseIdPrefix expression evalution will become the caseId

case var => CORRELATION_KEY=my correlation key
case var => IS_PREFIX_SEQUENCE=false
prefix = @{CORRELATION_KEY}

this will generate

caseId = my correlation key

Keep in mind that this would cause that this allows different sequence for the same case definition.

The last option would be to implement your own CaseIdGenerator and specify the class through property (only available in kie-server)

-Dorg.kie.server.cases.generator