Add a deprecated warning in abstract filter classes

src/ol/format/filter/and.js

@@ -7,6 +7,8 @@ goog.require('ol.format.filter.LogicalNary');
  * @classdesc
  * Represents a logical `<And>` operator between two or more filter conditions.
  *
+ * deprecated: This class will no longer be exported starting from the next major version.
+ *
  * @constructor
  * @abstract
  * @param {...ol.format.filter.Filter} conditions Conditions.

src/ol/format/filter/comparison.js

@@ -9,6 +9,8 @@ goog.require('ol.format.filter.Filter');
  * Abstract class; normally only used for creating subclasses and not instantiated in apps.
  * Base class for WFS GetFeature property comparison filters.
  *
+ * deprecated: This class will no longer be exported starting from the next major version.
+ *
  * @constructor
  * @abstract
  * @param {!string} tagName The XML tag name for this filter.

src/ol/format/filter/comparisonbinary.js

@@ -9,6 +9,8 @@ goog.require('ol.format.filter.Comparison');
  * Abstract class; normally only used for creating subclasses and not instantiated in apps.
  * Base class for WFS GetFeature property binary comparison filters.
  *
+ * deprecated: This class will no longer be exported starting from the next major version.
+ *
  * @constructor
  * @abstract
  * @param {!string} tagName The XML tag name for this filter.

src/ol/format/filter/filter.js

@@ -6,6 +6,8 @@ goog.provide('ol.format.filter.Filter');
  * Abstract class; normally only used for creating subclasses and not instantiated in apps.
  * Base class for WFS GetFeature filters.
  *
+ * deprecated: This class will no longer be exported starting from the next major version.
+ *
  * @constructor
  * @abstract
  * @param {!string} tagName The XML tag name for this filter.

src/ol/format/filter/spatial.js

@@ -10,6 +10,8 @@ goog.require('ol.format.filter.Filter');
  * Represents a spatial operator to test whether a geometry-valued property
  * relates to a given geometry.
  *
+ * deprecated: This class will no longer be exported starting from the next major version.
+ *
  * @constructor
  * @abstract
  * @param {!string} tagName The XML tag name for this filter.