1st sentence
 appended a prepositional phrase at the end of the first sentence ( diff), and on further reflection, that addition was deleted ( diff): 
"Japanese Americans are Americans of Japanese heritage, either born in Japan or their descendents."
I've restored those excised words. I think the qualifier phrase is necessary.  An Issei Japanese American currently serves in the U.S. House of Representatives, Congresswoman Mazie Hirono; and when I saw this trivial change, I thought of her immediately.  Although there is nothing incorrect in the phrase "Americans of Japanese descent," I wonder if the clarifying specificity of those extra words might not be necessary?  I wonder if others, like me, might otherwise tend to generalize in a way which inadvertently excludes this prominent woman and other Issei like her?

Maybe this small point has significance?