ph-schematron/src/main/java/com/helger/schematron/pure/preprocess/PSPreprocessor.java
@Nullable
  public PSSchema getAsMinimalSchema (@Nonnull final PSSchema aSchema) throws SchematronPreprocessException
  {
    ValueEnforcer.notNull (aSchema, "Schema");

    // Anything to do?
    if (aSchema.isMinimal ())
      return aSchema;

    return getForcedPreprocessedSchema (aSchema);
  }
@Nullable
  public PSSchema getAsMinimalSchema (@Nonnull final PSSchema aSchema) throws SchematronPreprocessException
  {
    ValueEnforcer.notNull (aSchema, "Schema");

    // Anything to do?
    if (aSchema.isMinimal ())
      return aSchema;

    return getForcedPreprocessedSchema (aSchema);
  }
Convert the passed schema to a minimal schema.

@param aSchema
The schema to be made minimal. May not be <code>null</code>
@return The original schema object, if it is already minimal - a minimal
copy otherwise! May be <code>null</code> if the original schema is
not yet minimal and {@link #isKeepEmptySchema()} is set to
<code>false</code>.
@throws SchematronPreprocessException
In case a preprocessing error occurs