core/src/main/java/com/orientechnologies/orient/core/index/OCompositeIndexDefinition.java
public void addIndex(final OIndexDefinition indexDefinition) {
    indexDefinitions.add(indexDefinition);
    if (indexDefinition instanceof OIndexDefinitionMultiValue) {
      if (multiValueDefinitionIndex == -1)
        multiValueDefinitionIndex = indexDefinitions.size() - 1;
      else
        throw new OIndexException("Composite key cannot contain more than one collection item");
    }

    collate.addCollate(indexDefinition.getCollate());
  }
public void addIndex(final OIndexDefinition indexDefinition) {
    indexDefinitions.add(indexDefinition);
    if (indexDefinition instanceof OIndexDefinitionMultiValue) {
      if (multiValueDefinitionIndex == -1)
        multiValueDefinitionIndex = indexDefinitions.size() - 1;
      else
        throw new OIndexException("Composite key cannot contain more than one collection item");
    }

    collate.addCollate(indexDefinition.getCollate());
  }
Add new indexDefinition in current composite.

@param indexDefinition Index to add.