You need to invoke the method, instead of getting it as codeModel will not parse your defined class:
JExpr.invoke(uutField, "getType");
which means your codemodel code will look like the following:
private void testDefaultConstructorMethod(JFieldVar uutField, JVar staticTYPEVar, final JDefinedClass unitTestClass, JDefinedClass definedClass, JCodeModel codeModel)
{
int modifiers = JMod.PUBLIC;
JMethod unitTestMethod = unitTestClass.method(modifiers, Void.TYPE, "testDefaultConstructor");
unitTestMethod.annotate(org.junit.Test.class);
JBlock unitTestBody = unitTestMethod.body();
unitTestBody.assign(uutField, JExpr._new(unitTestClass));
JClass abstractItemMetadataClass = definedClass._extends();
JInvocation assertEqualsInvoke = codeModel.ref(org.junit.Assert.class).staticInvoke("assertEquals").arg(staticTYPEVar).arg(JExpr.invoke(uutField, "getType"));
unitTestBody.add(assertEqualsInvoke);
}