However - if Java was Oracle to begin with (and as successful in the mid-90s) then might have done some marketing for the Java+Oracle mix.
Some people (ie Managers) if they decide on using Microsoft products will likely "encourage" the use of C# and .NET. -- That is an example of C# + Sql Server.
"I am using Java. Need a database - should it be Oracle?"
.NET Core 1.0 was released almost a _decade_ ago.