Bug 76507 [Encoding] properties dialog show BOM when there is no BOM
n20041017 The properties dialog for a file will say: Byte Order Mark is ... whenever the encoding for a file is determined from its contents (regardless a BOM was found or not). Test case: check with any *.properties files - it will say the file has a ISO 8859-1 BOM, which cannot true.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/IDEEncoding.java
if (WorkbenchEncoding.getDefinedEncodings().contains(value))
			return;
		writeEncodingsPreference(value, getIDEEncodingsPreference());
	}
	/**
	 * Write the encodings preference. If value is not null
	 * and not already in the list of currentEncodings add
	 * it to the list.
	 * @param value String or <code>null</code>
	 * @param encodings The list of encodings to write
	 */
	private static void writeEncodingsPreference(String value, Collection encodings) {
		boolean addValue = (value != null);
		StringBuffer result = new StringBuffer();
		Iterator currentEncodings = encodings.iterator();
		while (currentEncodings.hasNext()) {
			String string = (String) currentEncodings.next();
			result.append(string);
			result.append(PREFERENCE_SEPARATOR);
			if (addValue && string.equals(value))
				addValue = false;
		}
		if (addValue)
			result.append(value);
		IDEWorkbenchPlugin.getDefault().getPreferenceStore().setValue(IDE_ENCODINGS_PREFERENCE,
				result.toString());
	}
	/**
	 * Get the value of the encodings preference.
	 *