Automatic camel case breaking

TeX would linebreak (hyphenate) the camel case words, but perhaps not where you wish eg

cre-a-te-Un-spec-i-fiedNodeEr-ror-Marker

shows the default hyphenation points (using the default US English hyphenation)

It wasn't clear if you wanted hyphens at the break points. I have assumed not. If you do then change \penalty2 to \-.

This boxes the parts between capital letters so they don't break, and puts a small penalty before capitals so they can break.

As with anything using catcode changes (like \verb it will not work in the argument to another command)

\documentclass{scrartcl}

\showhyphens{createUnspecifiedNodeErrorMarker}

\makeatletter
\def\zzz{\leavevmode\begingroup
\let\ifcase\iftrue
\def\or##1{%
  \catcode`##1\active\uccode`\~`##1\uppercase{%
    \def~{\egroup\penalty2\hbox\bgroup\string##1}}}%
\@Alph{}%
\@zzz}

\def\@zzz#1{\textbf{\hbox\bgroup#1\egroup}\endgroup}
\makeatother

\begin{document}
\section{Test}


And another example the show must go on, but we have too less text (\zzz{createUnspecifiedNodeWarningMarker} and
\zzz{createUnspecifiedNodeErrorMarker}, sdjklashjksa \zzz{createUnspecifiedLinkWarningMarker} and
\zzz{createUnspecifiedLinkErrorMarker}).
\end{document}

An implementation in expl3 that also allows a (named) color as optional argument to \keyw:

\documentclass{article}
\usepackage{xcolor}
\usepackage{microtype}
\usepackage{xparse}

\ExplSyntaxOn
\NewDocumentCommand{\keyw}{O{.}m}
 {
  \textcolor{#1}{ \bfseries \cschulz_keyw:n { #2 } }
 }

\cs_new_protected:Nn \cschulz_keyw:n
 {
  \tl_map_inline:nn { #1 }
   {
    % if the current char is uppercase, add a discretionary hyphen
    \str_if_eq:eeT { ##1 } { \str_uppercase:n { ##1 } } 
     { \- }
    ##1
   }
 }
\ExplSyntaxOff

\begin{document}

\section{Test}

And another example the show must go on, but we have too less 
text (\keyw{createUnspecifiedNodeWarningMarker} sdjkle
\keyw{createUnspecifiedNodeErrorMarker}, sdjklashjksa 
\keyw{createUnspecifiedLinkWarningMarker} and
\keyw[red]{createUnspecifiedLinkErrorMarker}).

\end{document}

Expect several overfull boxes, anyway, as breaking only at capital letters is rather rigid.