Geoserver Dynamic Colormap using CQL won't validate

Question

I'm trying to create a dynamic heatmap using GeoServer 2.8.3, but when it comes to validating the colormap-part of my SLD i keep getting the same error:

line 66: cvc-datatype-valid.1.2.1: '${env('high',1)}' ist kein gültiger Wert für 'double'.
line 66: cvc-attribute.3: Wert '${env('high',1)}' des Attributs 'quantity' bei Element 'ColorMapEntry' hat keinen gültigen Typ 'double'.

My code looks as followed

<ColorMap type="ramp">
                <ColorMapEntry color="#FFFFFF" quantity="0" opacity="1.0"/>
                <ColorMapEntry color="#4444FF" quantity="0.3" opacity="1.0"/>
                <ColorMapEntry color="#FF0000" quantity="0.7" opacity="1.0"/>
                <ColorMapEntry color="#FFFF00" quantity="${env('high',1)}" opacity="1.0"/>
              </ColorMap>

While the first three entrys work just fine, the fourth is causing the error to appear. I am pretty confused since i took the code right from the documentation (http://docs.geoserver.org/2.8.x/en/user/styling/sld-reference/rastersymbolizer.html#cql-expressions). Since i want the colormap to be fully customizable by the getmap-method, i would like to make every colormap-entry (color aswell as quantity) dynamic using the env-function.

Putting in ('high',1.0) instead of ('high',1) wont work.

I also found another question regarding the same matter, but it didnt help either (How do I use env parameter variables in an SLD colormap?).

Did anyone experience something similar?

The dynamic quantitys do work, but once i apply the same to the colors, it won't display the map at all.

<ColorMap type="ramp">
                <ColorMapEntry color="${env('c1',#FFFFFF)}" quantity="${env('zero',0)}" opacity="1.0"/>
                <ColorMapEntry color="${env('c2',#4444FF)}" quantity="${env('low',0.3)}" opacity="1.0"/>
                <ColorMapEntry color="${env('c3',#FF0000)}" quantity="${env('med',0.7)}" opacity="1.0"/>
                <ColorMapEntry color="${env('c4',#FFFF00)}" quantity="${env('high',1)}" opacity="1.0"/>
              </ColorMap>

Do i have to do something special with the color-codes? I am not getting any error outputs for these.

Answer 1

Update: I found the solution and got a working SLD now. It is important to put the color codes in single quotes for GeoServer to recognize them as strings:

<ColorMapEntry color="${env('c4','#FFFF00')}" quantity="${env('high',1)}" opacity="1.0"/>

Upon validating I am still getting error messages, the SLD does work nonetheless. When accessing the variables through getMap, it is important to substitute the # with %23 in order for everything to work:

...&env=c1:%23DF7401;c2:%23BCA9F5&...