code: private void setConstantSpecs(EntitySpec[] constantParameterSpecs) {
          if (constantParameterSpecs == null) {
              this.constantSpecs = EMPTY_ES_ARR;
          } else {
              this.constantSpecs = constantParameterSpecs.clone();
          }
      }
docs: You can specify alternative versions of the same entity by creating
  sequential entity specs with the same name, different column specs for
  one or more properties or references, and mutually exclusive constraint
  specs. One example of where this is useful is inpatient versus clinic
  hospital encounters, for which dates might be stored differently.
  
  @param constantParameterSpecs