[kbss-cvut/termit-ui#581] Fix EntityExistsExceptions being thrown whe…

…n importing translations to more complex vocabularies.

src/main/java/cz/cvut/kbss/termit/service/importer/excel/ExcelImporter.java

@@ -256,6 +256,8 @@ public Vocabulary importTermTranslations(@Nonnull URI vocabularyIri, @Nonnull Im
                 }
                 mergeTranslations(t, existingTerm.get());
                 termService.update(existingTerm.get());
+                // Flush changes to prevent EntityExistsExceptions when term is already managed in PC as different type (Term vs TermInfo)
+                em.flush();
             });
         } catch (IOException e) {
             throw new VocabularyImportException("Unable to read input as Excel.", e);