code: public TableBuilder addConstraint(String columnName, String constraintType, String constraintConflictClause) {
          constraints.add(new Constraint(columnName, constraintType, constraintConflictClause));
          return this;
      }
docs: Adds the specified constraint to the created table.
  
  @param columnName               The name of the column on which the constraint is applied.
  @param constraintType           The type of constraint to apply.
  One of
  <ul>
  <li>{@link com.tjeannin.provigen.model.Constraint#UNIQUE}</li>
  <li>{@link com.tjeannin.provigen.model.Constraint#NOT_NULL}</li>
  </ul>
  @param constraintConflictClause The conflict clause to apply in case of constraint violation.
  One of
  <ul>
  <li>{@link com.tjeannin.provigen.model.Constraint.OnConflict#ABORT}</li>
  <li>{@link com.tjeannin.provigen.model.Constraint.OnConflict#FAIL}</li>
  <li>{@link com.tjeannin.provigen.model.Constraint.OnConflict#IGNORE}</li>
  <li>{@link com.tjeannin.provigen.model.Constraint.OnConflict#REPLACE}</li>
  <li>{@link com.tjeannin.provigen.model.Constraint.OnConflict#ROLLBACK}</li>
  </ul>
  @return The {@link com.tjeannin.provigen.helper.TableBuilder} instance to allow chaining.