beginGL() now returns a PGL object that is part of the Processing core and exposes only a subset of the OpenGL calls (basically those that are part of OpenGL ES 2.0). But you can still retrieve the JOGL object that gives you access to the entire GL API. It is just a member of PGL:
This is due to changes in JOGL itself. Processing 1.5.1 used JOGL 1.1, while Processing 2.0 uses JOGL 2.0.
In JOGL 2, the GL functions that correspond to different "profiles" (GL1, GL2.1, GL3, etc) are accessed through different GL objects. The glColor4f() function, for instance, is accessed through the GL2 profile object:
GL2 gl2 = gl.getGL2();
All this increased complexity in JOGL is what prompted us to add the PGL interface, but it only covers a small subset of the GL API.