fix: MainTest#checkModelIsTree needs less memory

[pvojtechovsky]

Should solve OutOfMemoryException in CI

[spoon-bot]

Revapi Analysis results

Old API: fr.inria.gforge.spoon:spoon-core:jar:6.0.0-20171012.192256-75

New API: fr.inria.gforge.spoon:spoon-core:jar:6.0.0-SNAPSHOT

Detected changes: 6.

Change 1

Name	Element
Old	method void spoon.support.visitor.clone.CloneVisitor::()
New	method void spoon.support.visitor.clone.CloneVisitor::(spoon.support.visitor.equals.CloneHelper)
Code	java.method.numberOfParametersChanged
Description	The number of parameters of the method have changed.
Breaking	binary: breaking

Change 2

Name	Element
Old	method java.util.Collection spoon.support.visitor.equals.CloneHelper::clone(java.util.Collection)
New	method java.util.Collection spoon.support.visitor.equals.CloneHelper::clone(java.util.Collection)
Code	java.method.noLongerStatic
Description	method no longer static
Breaking	binary: breaking

Change 3

Name	Element
Old	method java.util.List spoon.support.visitor.equals.CloneHelper::clone(java.util.List)
New	method java.util.List spoon.support.visitor.equals.CloneHelper::clone(java.util.List)
Code	java.method.noLongerStatic
Description	method no longer static
Breaking	binary: breaking

Change 4

Name	Element
Old	method java.util.Map<java.lang.String, T> spoon.support.visitor.equals.CloneHelper::clone(java.util.Map<java.lang.String, T>)
New	method java.util.Map<java.lang.String, T> spoon.support.visitor.equals.CloneHelper::clone(java.util.Map<java.lang.String, T>)
Code	java.method.noLongerStatic
Description	method no longer static
Breaking	binary: breaking

Change 5

Name	Element
Old	method java.util.Set spoon.support.visitor.equals.CloneHelper::clone(java.util.Set)
New	method java.util.Set spoon.support.visitor.equals.CloneHelper::clone(java.util.Set)
Code	java.method.noLongerStatic
Description	method no longer static
Breaking	binary: breaking

Change 6

Name	Element
Old	method T spoon.support.visitor.equals.CloneHelper::clone(T)
New	method T spoon.support.visitor.equals.CloneHelper::clone(T)
Code	java.method.noLongerStatic
Description	method no longer static
Breaking	binary: breaking