1. A computer-implemented method for supporting migration of unstructured data stored in enterprise content management systems, comprising: generating a search for the unstructured data matching at least one content search rule, the unstructured data comprising information that does not have a predefined data model, the at least one content search rule comprising an enterprise identifier and a document identifier and the at least one content search rule being retrieved from a migration engine server configured to provide support for migration of the unstructured data and structured data stored in an enterprise resource planning system; receiving a list of matched documents, wherein each document in the list of matched documents comprises at least a portion of the unstructured data and is associated with at least a source repository identifier and a unique document identifier; calculating a target repository identifier and at least one metadata change instruction for each unique document identifier using at least one migration rule defining how the unstructured data is to be migrated to maintain an integrity of the unstructured data, the at least one migration rule being compliant with international regulations; and modifying metadata for the document associated with the document identifier using the calculated at least one metadata change instruction to generate a modified copy of the document, the at least one metadata change instruction specifying that any matched content with a particular source repository identifier is to be modified to reflect a particular target repository identifier, the particular target repository identifier comprising at least one of a prefix and a suffix different from the particular source repository identifier and the at least one metadata change instruction specifying deletion of the metadata matching the particular source repository identifier from a source repository associated with the particular source repository identifier upon migration to a target repository associated with the particular target repository identifier.