Hi,
Spring Data Couchbase 1.4.2 is based on the “older” generation of SDKs (Java SDK 1.4.2 as well). Cross-compatibility between SDKs was not supported with this generation and was a focus of the second generation of SDKs (to which the .NET 2.2.2 belongs, but not the Java 1.4.2 one).
Second-generation Spring Data Couchbase 2.0.x is currently in Release Candidate and should produce documents that are cross-compatible with .NET 2.2.2.