Given the following context:

Nielsen wrote three concertos: the Violin Concerto, Op. 33 is a middle-period work, from 1911, which lies within the tradition of European classicism, whereas the Flute Concerto (without opus number) of 1926 and the Clarinet Concerto, Op. 57 which followed in 1928 are late works, influenced by the modernism of the 1920s and, according to the Danish musicologist Herbert Rosenberg, the product of "an extremely experienced composer who knows how to avoid inessentials." Unlike Nielsen's later works, the Violin Concerto has a distinct, melody-oriented neo-classical structure. The Flute Concerto, in two movements, was written for the flautist Holger Gilbert-Jespersen, a member of the Copenhagen Wind Quintet which had premiered Nielsen's Wind Quintet (1922). In contrast to the rather traditional style of the Violin Concerto, it reflects the modernistic trends of the period. The first movement, for example, switches between D minor, E-flat minor and F major before the flute comes to the fore with a cantabile theme in E major. The Clarinet Concerto was also written for a member of the Copenhagen Wind Quintet, Aage Oxenvad. Nielsen stretches the capacities of instrument and player to the utmost; the concerto has just one continuous movement and contains a struggle between the soloist and the orchestra and between the two principal competing keys, F major and E major.The wind concertos present many examples of what Nielsen called objektivering ("objectification"). By this term he meant giving instrumentalists freedom of interpretation and performance within the bounds set out by the score.

answer the following question:

What was the name of the composer who Rosenberg said knew how to avoid inessentials? 

Nielsen